JP6138378B2 - Fuel cell system - Google Patents

Description

  The present invention relates to an operation stop process of a fuel cell system.

  In general, a solid oxide fuel cell system supplies a hydrogen-containing gas and air to a fuel cell, which is a main body of a power generation unit, and generates chemical energy generated by an electrochemical reaction between hydrogen and oxygen in the air. Is a system that generates electricity as electrical energy. During the steady operation of the solid oxide fuel cell system, the solid oxide fuel cell operates at a high temperature of 500 ° C to 900 ° C.

  The solid oxide fuel cell system includes a hydrogen generator for generating a hydrogen-containing gas (reformed gas). The hydrogen generation apparatus uses a fossil raw material such as city gas mainly composed of natural gas or LPG as a raw material (power generation raw material) for generating a hydrogen-containing gas. The hydrogen generator is provided with a reformer, and this reformer reacts the power generation raw material with water vapor (reforming reaction) at a high temperature of about 600 ° C. using, for example, a Ru catalyst or a Ni catalyst, A contained gas is generated. The reformer is maintained at a high temperature of 400 ° C. to 700 ° C. during the steady operation of the solid oxide fuel cell system, and is continuously supplied with power generation raw materials and water, and contains hydrogen by a reforming reaction by a catalyst. Generate gas.

  The solid oxide fuel cell system also includes an evaporator that generates water vapor necessary for the reforming reaction in the reformer from water supplied from the outside. The evaporator is maintained at a high temperature of 100 ° C. to 300 ° C. during the steady operation of the solid oxide fuel cell system.

  By the way, in the operation stop process executed when the operation of the solid oxide fuel cell system is stopped, the fuel cell, the reformer, the evaporator, etc. operating at a high temperature are cooled to a predetermined temperature, and the reformer It is necessary to purge the hydrogen-containing gas remaining inside, the fuel cell, and the flow path through which the hydrogen-containing gas flows. This is for the following reason. Since the remaining hydrogen-containing gas contains water vapor, water condenses when the temperature falls below the dew point during the cooling process. At that time, air enters from the outside due to a pressure drop. Therefore, the anode material is oxidized by the invading air. Therefore, if the start and stop are repeated, oxidation and reduction of the anode material are repeated, which causes a significant decrease in durability. And this condensed water causes the durability of the catalyst charged in the reformer or desulfurizer other than the anode to be significantly reduced. Note that a process including a plurality of processing steps including, for example, the above-described purge, which is performed when the operation of the solid oxide fuel cell system is stopped, is referred to as an operation stop process. The operation stop process is a process from the reception of the power generation stop instruction until the supply of the hydrogen-containing gas and the oxidant gas is stopped. The supply stop of the hydrogen-containing gas and the oxidant gas is, for example, a solid oxide fuel The configuration may be performed when the battery stack temperature or the reformer temperature reaches a predetermined temperature (for example, 100 degrees).

  2. Description of the Related Art A solid oxide fuel cell system having a configuration in which a hydrogen-containing gas is purged by creating a reducing atmosphere using an inert gas such as nitrogen in this shutdown process has been known. However, in the case of purging using an inert gas in this way, it is necessary to install a dedicated flow path for purging, and there is a problem that the solid oxide fuel cell system is increased in size. Therefore, a fuel cell system that purges a hydrogen-containing gas using a source gas has been proposed (for example, Patent Document 1).

JP 2013-186945 A

  The present invention provides a fuel cell system that can safely stop operation while preventing a decrease in durability.

  In order to solve the above problems, a fuel cell system according to the present invention supplies a solid oxide fuel cell and a hydrogen-containing gas generated by reforming a power generation raw material to the anode of the solid oxide fuel cell. A reformer, a power generation raw material supply device that supplies the power generation raw material to the reformer, and at least one of reforming water and air used in a reforming reaction with respect to the reformer A reforming material supplier to be supplied, an oxidant gas supplier for supplying an oxidant gas to the cathode of the solid oxide fuel cell, and an igniter for igniting exhaust gas discharged from the solid oxide fuel cell A fuel cell system comprising: a combustion section having a controller; and a controller, wherein in the operation stop process of the fuel cell system, the controller controls the oxidant gas supply device to supply the oxidant gas. Solid oxide fuel And supplying the power generation raw material feeder and the reforming material supply device to supply the power generation raw material and at least one of the water and air intermittently to the reformer. At the same time, the ignition unit included in the combustion unit is controlled to perform an ignition operation.

  In order to solve the above-described problems, the fuel cell system according to the present invention supplies a solid oxide fuel cell and a hydrogen-containing gas generated by reforming a power generation raw material to the solid oxide fuel cell. A reforming device, a power generation raw material supply device for supplying the power generation raw material to the reformer, a reforming water supply device for supplying water to be used for a reforming reaction in the reformer to the reformer, An evaporator for vaporizing water supplied to the reformer from the reformed water supplier, a heater for heating the evaporator, and an oxidant gas for supplying an oxidant gas to the solid oxide fuel cell A combustible gas flow path that is a flow path from the power generation raw material supply device to the solid oxide fuel cell, through which the power generation raw material or the hydrogen-containing gas that is a combustible gas flows, and the oxidant The solid acid from the oxidant gas supply device through which gas flows Detects the temperature of at least one of the temperature of the evaporator, the reformer, and the solid oxide fuel cell that change in conjunction with the oxidant gas flow path, which is a flow path to the physical fuel cell. And a controller for controlling the operation of the solid oxide fuel cell, wherein the controller controls the power generation material supply device and the reforming water supply device to generate the power generation material. And water are circulated through the combustible gas flow path, and the oxidant gas is circulated through the oxidant gas flow path by controlling the oxidant gas supply unit. Based on the above, when it is determined that the operating temperature of the evaporator is equal to or lower than the lower limit value, the evaporator is controlled to be heated by the heater.

  The fuel cell system according to the present invention is configured as described above, and has an effect that the operation can be safely stopped while preventing a decrease in durability. Furthermore, the configuration in which the power generation raw material and at least one of water and air are intermittently supplied to the reformer is faster than the configuration in which the power generation raw material is continuously supplied to the reformer. There is also an effect that the temperature of the solid oxide fuel cell and the reformer can be lowered.

It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the time-sequential change of each part when a fuel cell system operate | moves according to the flowchart shown in FIG. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 1 of Embodiment 1 of this invention. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 2 of Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 2 of Embodiment 1 of this invention. It is a figure which shows an example of the time series change of each part when a fuel cell system operate | moves according to the flowchart shown in FIG. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 3 of Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 3 of Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 4 of Embodiment 1 of this invention. It is a figure which shows an example of the time-sequential change of each part when a fuel cell system operate | moves according to the flowchart shown in FIG. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 5 of Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 5 of Embodiment 1 of this invention. It is a figure which shows an example of the time-sequential change of each part when a fuel cell system operate | moves according to the flowchart shown in FIG. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 6 of Embodiment 1 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 6 of Embodiment 1 of this invention. It is a figure which shows an example of the time series change of each part when a fuel cell system operate | moves according to the flowchart shown in FIG. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on Embodiment 2 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on Embodiment 2 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on Embodiment 2 of this invention. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 1 of Embodiment 2 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 1 of Embodiment 2 of this invention. It is a flowchart which shows an example of the operation stop process of the fuel cell system which concerns on the modification 1 of Embodiment 2 of this invention. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 2 of Embodiment 2 of this invention. It is a block diagram which shows an example of schematic structure of the fuel cell system which concerns on the modification 3 of Embodiment 2 of this invention.

(Background to obtaining one embodiment of the present invention)
As a result of earnest research on the fuel cell system according to Patent Document 1 described in “Background Art”, the present inventors have obtained the following knowledge.

  That is, in the case of a fuel cell system in which purging is performed using a raw material gas (power generation raw material) as in Patent Document 1, it has been found that the power generation raw material that is a combustible gas is discharged out of the system as it is. In addition, when the power generation raw material is supplied to the reformer in the high temperature state after the shutdown or the anode of the fuel cell, the hydrocarbon raw material is decomposed and carbon deposited at the reformer or the anode, thereby the reformer or It has been found that the anode can break.

  Based on the above findings, the present inventors have found that the operation can be safely stopped by burning the combustible power generation raw material used for the purge before exhausting out of the system. It has also been found that carbon deposition at the reformer or anode of a solid oxide fuel cell can be prevented by purging with a hydrogen-containing gas (reformed gas) obtained by reforming the power generation material instead of the power generation material. The present invention has been reached. The present invention specifically provides the following modes.

  Furthermore, the present inventors have earnestly studied the fuel cell system according to Patent Document 1 described in “Background Art”, and have obtained the following knowledge.

  In Patent Document 1, it is necessary to supply a purge gas (for example, a power generation raw material) to the anode even when the stack temperature of the fuel cell is a low temperature of about 150 ° C. to 300 ° C. in the operation stop process. I found out. This is because when the purge gas is not supplied to the anode, air flows from the outside to the downstream side of the anode, a local battery is formed between the upstream portion of the anode and the downstream portion of the anode, and the anode material is oxidized. Because there is a possibility of doing.

  Further, when the fuel cell system is configured to mix the anode off-gas and the cathode off-gas on the downstream side of the fuel cell, the purge gas (for example, oxidant gas) is supplied to the cathode in the operation stop process. Is stopped and the purge gas (for example, power generation raw material) is supplied only to the anode, the purge gas supplied to the anode may flow in from the downstream side of the cathode. This is because the reformed water remaining in the system after the fuel cell stops evaporates due to excess heat, and the pressure of the anode of the fuel cell is higher than that of the cathode. As described above, when the purge gas supplied to the anode flows into the cathode, the cathode material may be reduced and the performance of the fuel cell may be deteriorated.

  Based on the above knowledge, the present inventors are configured to supply a hydrogen-containing gas (reformed gas) to the anode and an oxidant gas to the cathode until the stack temperature of the fuel cell decreases to about 150 ° C. By doing so, it was found that oxidation of the anode and reduction of the cathode can be prevented. Further, in order to supply a hydrogen-containing gas (reformed gas) generated by reforming the raw material gas in a predetermined temperature range where the hydrocarbon raw material is decomposed and carbon deposition occurs, the power generation raw material is supplied to the anode. The inventors have found that the carbon deposition that occurs in can be prevented, and have reached the present invention. The present invention specifically provides the following modes.

  A fuel cell system according to a first aspect of the present invention includes a solid oxide fuel cell and a reformer that supplies a hydrogen-containing gas generated by reforming a power generation raw material to the anode of the solid oxide fuel cell. A power generation raw material supplier that supplies the power generation raw material to the reformer; and a reformer that supplies at least one of reforming water and air used in a reforming reaction to the reformer Combustion section having a material supplier, an oxidant gas supplier for supplying an oxidant gas to the cathode of the solid oxide fuel cell, and an igniter for igniting the exhaust gas discharged from the solid oxide fuel cell And a controller, wherein in the operation stop process of the fuel cell system, the controller controls the oxidant gas supply unit to convert the oxidant gas into the solid oxide. Used for cathode of fuel cell And controlling the power generation material supplier and the reforming material supplier to intermittently supply the power generation material and at least one of the water and air to the reformer, and the combustion An ignition operation is performed by controlling the igniter of the unit.

  According to the above configuration, since the controller controls the oxidant gas supply device to supply the oxidant gas to the cathode of the solid oxide fuel cell, the oxidant gas supplies the solid oxide fuel from the oxidant gas supply device. Purge along the path to the battery cathode can be performed. Further, the controller controls the power generation raw material supply device and the reforming material supply device to intermittently supply the power generation raw material and at least one of water and air to the reformer. That is, the hydrogen-containing gas generated by the reforming reaction in the reformer using the power generation raw material and at least one of water and air can be intermittently supplied to the anode of the solid oxide fuel cell. . For this reason, purging can be performed in the path from the reformer to the anode of the solid oxide fuel cell with the hydrogen-containing gas. Further, since the hydrogen-containing gas used for purging is not exposed to a high temperature like hydrocarbon raw materials such as power generation raw materials, carbon deposition does not occur, so that it is possible to prevent a decrease in durability of the fuel cell system due to carbon deposition.

  The oxidant gas and hydrogen-containing gas supplied to the solid oxide fuel cell are exhausted from the solid oxide fuel cell as exhaust gas. The exhaust gas can be ignited and combusted by an igniter in the combustion section. Therefore, it is possible to prevent the combustible gas from being discharged out of the fuel cell system as it is.

  Therefore, the fuel cell system according to the first aspect of the present invention has an effect that the operation can be safely stopped while preventing a decrease in durability. Furthermore, a configuration in which power generation raw materials and the like are continuously supplied to the reformer by a configuration in which power generation raw materials and at least one of water and air (hereinafter referred to as power generation raw materials) are intermittently supplied to the reformer. As compared with the above, there is an effect that the temperature of the solid oxide fuel cell and the reformer can be lowered more quickly. For example, in the operation of stopping the operation of the fuel cell system, in the case of a configuration in which the power generation raw material or the like is continuously supplied to the reformer, the supply device that supplies the power generation raw material or the like continuously operates. That is, even when the supply of power generation raw materials or the like is not necessary, the power generation raw materials or the like having a minimum flow rate are fed from the feeder and the exhaust gas discharged from the solid oxide fuel cell is continuously burned. On the other hand, since the fuel cell system according to the first aspect of the present invention is configured to intermittently supply power generation raw materials and the like, the exhaust gas discharged from the solid oxide fuel cell is continuously burned. Can be prevented. Therefore, the fuel cell system according to the first aspect of the present invention lowers the temperature of the solid oxide fuel cell, the reformer, etc. faster than the configuration in which the power generation raw material is continuously supplied. Can do.

  Further, the fuel cell system according to the second aspect of the present invention is the combustible gas included in the combustion exhaust gas provided in the downstream side of the combustion part and discharged from the combustion part in the first aspect described above. And a purifier temperature detector for detecting the temperature of the purifier as a temperature detector for detecting the temperature of the fuel cell system, and the detection by the purifier temperature detector When the result is less than a predetermined temperature, the controller may be configured to control the igniter to perform an ignition operation.

  Here, the predetermined temperature is, for example, a lower limit value of the temperature at which the purification catalyst included in the purifier is activated.

  According to the above configuration, when the purifier temperature is equal to or higher than the predetermined temperature, the igniter is not operated and the combustible gas is purified by the purifier. On the other hand, when the temperature of the purifier is lower than the predetermined temperature, the controller has not reached the temperature at which the purifying catalyst is activated. Therefore, the controller operates the igniter to burn the combustible gas in the combustion section.

  Therefore, in the fuel cell system, the purification of the remaining combustible gas can be achieved by combining a purifier capable of purifying the combustible gas at a temperature lower than that of the combustion portion and a combustion portion for burning and purifying the combustible gas. Can be achieved more reliably, and the amount of heat required in the combustion section can be suppressed. Therefore, the temperature of the fuel cell system can be more reliably and efficiently reduced as compared with the configuration in which the combustible gas is purified only by the combustion part. In addition, since the amount of heat required in the combustion section and the supply amount of raw materials can be suppressed, it is possible to reduce energy consumption and shorten the stop time in the stop operation of the fuel cell system.

  Further, the fuel cell system according to the third aspect of the present invention may include a desulfurizer for removing sulfur compounds contained in the power generation raw material in the first or second aspect described above. Good.

  According to the said structure, since a desulfurizer is provided, the sulfur compound contained in an electric power generation raw material can be removed. For this reason, it can prevent that the reforming catalyst of the reformer located downstream from the desulfurizer is poisoned by the sulfur compound contained in the power generation raw material.

  The fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the third aspect described above, wherein the exhaust gas burned in the combustion section is circulated, and the desulfurizer is turned on by the heat of the burned exhaust gas. You may be comprised so that the heating part to heat may be provided.

  According to the said structure, since a heating part is provided, the heat | fever which the waste gas burned has can be utilized effectively, and a desulfurizer can be heated.

  In the fuel cell system according to the fifth aspect of the present invention, in the third or fourth aspect described above, the desulfurizer is a hydrodesulfurizer that removes sulfur compounds from the power generation raw material using hydrogen. It may be.

  The fuel cell system according to a sixth aspect of the present invention is the fuel cell system according to any one of the first to fifth aspects described above, wherein the controller includes at least one of the power generation raw material, the water and air. The intermittent supply to either one of the reformers may be performed by operating the power generation material supply device and the reforming material supply device at predetermined time intervals.

  According to the above configuration, the controller can intermittently supply the power generation raw material and at least one of water and air to the reformer at predetermined time intervals. For this reason, purging in the path from the reformer to the anode of the solid oxide fuel cell can be performed with the hydrogen-containing gas while suppressing the consumption of the power generation raw material, compared to the configuration in which the power generation raw material is always supplied. .

  The fuel cell system according to a seventh aspect of the present invention is the fuel cell system according to any one of the third to fifth aspects described above, wherein the reformer, the solid oxide fuel cell, and the desulfurizer. The temperature of the fuel cell system changes in conjunction with each other, and as a temperature detection unit for detecting the temperature of the fuel cell system, a reformer temperature detection unit for detecting the temperature of the reformer, and the solid oxide fuel cell At least one of a fuel cell temperature detection unit for detecting temperature and a desulfurizer temperature detection unit for detecting the temperature of the desulfurizer, and the controller includes the power generation raw material, the water and air At least one of the intermittent supply to the reformer was detected by at least one of the reformer temperature detector, the fuel cell temperature detector, and the desulfurizer temperature detector. Temperature Depending on whether the temperature range may be configured to perform controls the power generation raw material supply unit and the reforming material feeder.

  Here, since the temperatures of the reformer, the solid oxide fuel cell, and the desulfurizer change in conjunction with each other, each temperature change in each part is stored in association with each other, so that The temperature change of another member can be grasped from the temperature change.

  According to the above configuration, the controller intermittently supplies the power generation raw material and at least one of water and air to the reformer, at least the reformer temperature detection unit, the fuel cell temperature detection unit, and the desulfurization. This can be performed depending on whether the temperature detected by any one of the temperature detectors is within a predetermined temperature range. By the way, the predetermined temperature range used for determining whether or not to intermittently supply the power generation raw material and at least one of water and air to the reformer is, for example, a reformer, a solid oxide form, or the like. The fuel cell and the desulfurizer can be determined within a range where the temperature does not become excessive.

  For this reason, the fuel cell system according to the seventh aspect is characterized in that the reformer, the solid oxide fuel cell, and the desulfurizer are monitored from the reformer by the hydrogen-containing gas while monitoring so as not to overheat. Purging can be performed in the path leading to the anode of the fuel cell.

  In the fuel cell system according to the eighth aspect of the present invention, in the seventh aspect described above, the controller is configured to supply the reformer with the power generation raw material and at least one of the water and air. Is intermittently supplied according to at least a rise value and a fall value of the temperature detected by any one of the reformer temperature detection unit, the fuel cell temperature detection unit, and the desulfurizer temperature detection unit, The power generation raw material supply device and the reforming material supply device may be configured to be controlled.

  A fuel cell system according to a ninth aspect of the present invention is the fuel cell system according to any one of the first to fifth aspects described above, from the power generation raw material supply device to the anode of the solid oxide fuel cell. A flammable gas flow path through which the flammable gas containing the power generation raw material flows, a pressure sensor provided in the flammable gas flow path for detecting the pressure in the flammable gas flow path, When the pressure in the combustible gas flow path becomes a negative pressure in the detection result of the pressure sensor, the controller includes the power generation raw material and at least one of the water and air. The intermittent supply to the reformer may be performed by operating the power generation raw material supply device and the reforming material supply device at predetermined time intervals.

  According to the above configuration, when the pressure in the combustible gas flow path becomes negative, the controller intermittently supplies the power generation raw material and at least one of water and air to the reformer for a predetermined time. Do this at every interval. For this reason, the combustible gas flow path is monitored so that air does not flow in from the outside, and in the case of negative pressure, the power generation raw material and at least one of water and air are supplied. The pressure of the combustible gas channel can be increased.

  Therefore, in the fuel cell system according to the ninth aspect, purge is performed in a path from the reformer to the anode of the solid oxide fuel cell by the hydrogen-containing gas while preventing air from flowing into the combustible gas flow path from the outside. It can be performed.

  The fuel cell system according to a tenth aspect of the present invention is the fuel cell system according to any one of the first to fifth aspects, further comprising a voltage detector that detects the voltage of the solid oxide fuel cell. Each time the voltage detected by the voltage detector falls below a predetermined voltage, the controller supplies the power generation raw material and at least one of the water and air to the reformer. The power generation raw material supplier and the reforming material supplier may be controlled.

  Here, the predetermined voltage is a voltage that can be detected in the solid oxide fuel cell when the pressure of the combustible gas flow path becomes negative and air flows in from the outside.

  According to the above configuration, the controller supplies the power generation raw material and at least one of water and air to the reformer each time the voltage of the solid oxide fuel cell detected by the voltage detector becomes a predetermined voltage or less. Can be supplied. That is, it can be determined whether or not the combustible gas flow path has become a negative pressure from the voltage drop of the solid oxide fuel cell. More specifically, when the combustible gas flow path has a negative pressure, air enters from the outside, and the oxygen partial pressure at the anode increases, so the potential difference between the cathode and the anode decreases, and the solid oxide fuel Battery voltage decreases. For this reason, in a state where the voltage of the solid oxide fuel cell is higher than a predetermined temperature (for example, 120 ° C.) at which sensing is possible, when the voltage becomes lower than the predetermined voltage, the combustible gas flow path becomes negative pressure and air enters from the outside. I understand that. Therefore, when the voltage of the solid oxide fuel cell is equal to or lower than the predetermined voltage, the pressure of the combustible gas flow path is increased by supplying the power generation raw material and at least one of water and air, and from the outside. Intrusion of air can be suppressed.

  Therefore, in the fuel cell system according to the tenth aspect, the purge in the path from the reformer to the anode of the solid oxide fuel cell is performed by the hydrogen-containing gas while preventing air from flowing into the combustible gas flow path from the outside. It can be performed.

  The fuel cell system according to an eleventh aspect of the present invention is the reforming material used in the reforming reaction with respect to the reformer in the ninth aspect described above. A reforming water supply device for supplying water, an evaporator for vaporizing water supplied from the reforming water supply device to the reformer, a heater for heating the evaporator, and the oxidizing agent An oxidant gas flow path, which is a flow path from the oxidant gas supply unit to the solid oxide fuel cell, through which gas flows, the evaporator, the reformer, and the solid oxide type The temperature of the fuel cell changes in conjunction with each other. As a temperature detection unit for detecting the temperature of the fuel cell system, an evaporator temperature detection unit for detecting the temperature of the evaporator, and a temperature of the reformer are detected. Reformer temperature detector, and the temperature of the solid oxide fuel cell At least one of the fuel cell temperature detectors to be detected, and in the operation stop step of the fuel cell system, the controller controls the power generation raw material supplier and the reforming water supplier. The power generation raw material and water are circulated through the combustible gas flow path, the oxidant gas supply device is controlled to circulate the oxidant gas through the oxidant gas flow path, and the temperature When it determines with the operating temperature of the said evaporator becoming below a lower limit based on the detection result of a detection part, you may be comprised so that the said evaporator may be heated with the said heater.

  According to the above configuration, the controller controls the heater to heat the evaporator when it is determined that the operating temperature of the evaporator has become a lower limit value or less. For this reason, in accordance with the temperature drop in the fuel cell shutdown process, the evaporator cannot sufficiently evaporate water, and it is possible to prevent a problem that the reforming reaction does not proceed sufficiently in the reformer. Can do. Therefore, it is possible to continuously generate the hydrogen-containing gas in the reformer even in the fuel cell shutdown process, and to purge the combustible gas channel with the hydrogen-containing gas.

  A fuel cell system according to a twelfth aspect of the present invention includes a fuel cell, a reformer that supplies a hydrogen-containing gas generated by reforming a power generation material to the fuel cell, and the power generation material as the reformer. The power generation raw material supply device to be supplied to the reformer, the reforming water supply device to supply water to be used for the reforming reaction in the reformer to the reformer, and the reforming water supply device to be supplied to the reformer An evaporator that vaporizes water, a heater that heats the evaporator, an oxidant gas supplier that supplies an oxidant gas to the fuel cell, and the power generation raw material or the hydrogen-containing gas that is a combustible gas A combustible gas flow path that is a flow path from the power generation raw material supply unit to the fuel cell, and an oxidation that is a flow path from the oxidant gas supply unit to the fuel cell through which the oxidant gas flows. The evaporator gas flow changing in conjunction with the agent gas flow path, the reforming A temperature detection unit that detects at least one of the temperatures of the fuel cell, and a controller, and in the operation stop step of the fuel cell, the controller includes the power generation material supplier The reforming water supplier is controlled to cause the power generation raw material and water to flow through the combustible gas channel, and the oxidant gas supplier is controlled to supply the oxidant gas to the oxidant gas channel. When it is determined that the operating temperature of the evaporator has become a lower limit value or less based on the detection result of the temperature detector, the heater is controlled to be heated by the heater.

  Here, the lower limit value of the operating temperature of the evaporator is the lower limit value of the temperature of the evaporator that is required to vaporize water.

  According to the said structure, a controller distribute | circulates an electric power generation raw material and water to a combustible gas flow path in the operation stop process of a fuel cell. For this reason, the power generation raw material and water become hydrogen-containing gas by the reforming reaction in the reformer, and the combustible gas flow path can be purged by the hydrogen-containing gas. As described above, the combustible gas flow path can be purged with the hydrogen-containing gas, so that the combustible gas generated by the pressure drop accompanying the gas contraction in the combustible gas flow path and the water vapor condensing as the temperature decreases. Air can be prevented from flowing in from the outside in accordance with the pressure drop in the flow path. Therefore, in addition to oxidation by air on the downstream side of the anode at low temperatures, oxidation due to local battery generation on the upstream side of the anode due to intrusion of air from the downstream side of the anode can be suppressed.

  Further, since the combustible gas flow path is purged with a hydrogen-containing gas, even when the operation is stopped in a high temperature state, it is decomposed, for example, as a power generation raw material, and the reforming catalyst of the fuel cell anode and reformer No carbon deposition occurs. For this reason, deterioration of the anode and the reforming catalyst can be prevented, and durability can be improved.

  The controller causes the oxidant gas to flow through the oxidant gas flow path. For this reason, since the inside of the oxidant gas flow path can be purged by the oxidant gas, the hydrogen-containing gas is prevented from flowing into the oxidant gas flow path from the combustible gas flow path in the fuel cell shutdown process. be able to.

  In addition, when it is determined that the operating temperature of the evaporator has become a lower limit value or less, the controller controls the heater to be heated by the heater. For this reason, in accordance with the temperature drop in the fuel cell shutdown process, the evaporator cannot sufficiently evaporate water, and it is possible to prevent a problem that the reforming reaction does not proceed sufficiently in the reformer. Can do. Therefore, it is possible to continuously generate the hydrogen-containing gas in the reformer even in the fuel cell shutdown process, and to purge the combustible gas channel with the hydrogen-containing gas.

  Therefore, the fuel cell system according to the present invention has an effect that the operation can be stopped while improving the durability.

  The fuel cell system according to a thirteenth aspect of the present invention is the purifier for purifying the exhaust gas containing the combustible gas and the oxidant gas discharged from the fuel cell in the twelfth aspect. The temperature detector detects at least one of the temperatures of the evaporator, the reformer, and the fuel cell, and the temperature of the purifier that changes in conjunction therewith. It may be configured to.

  A fuel cell system according to a fourteenth aspect of the present invention is the fuel cell system according to the twelfth or thirteenth aspect, provided separately from the reformer, reforming a power generation raw material, A pre-reformer for supplying, and when the controller determines that the operating temperature of the evaporator has become a lower limit value or less based on the detection result of the temperature detector, the controller uses the heater together with the evaporator. The configuration may be such that the pre-reformer is controlled to be heated.

  According to the above configuration, the pre-reformer is provided, and the pre-reformer is heated by the heater together with the evaporator. For this reason, even if the reforming reaction does not proceed sufficiently in the reformer due to the temperature drop of the reformer after the fuel cell is stopped, it is heated by a heater instead of the reformer. The reforming reaction can be advanced by the preliminary reformer.

  Therefore, in the fuel cell system according to the fourteenth aspect of the present invention, the hydrogen-containing gas is continuously generated in the reformer even in the fuel cell shutdown process, and the combustible gas flow path is generated by the hydrogen-containing gas. Can be purged.

  Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. In the following, the same or corresponding components are denoted by the same reference numerals throughout all the drawings, and the description thereof is omitted.

[Embodiment 1]
(Configuration of fuel cell system)
First, the configuration of a fuel cell system 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an example of a schematic configuration of a fuel cell system 100 according to Embodiment 1 of the present invention. The fuel cell system 100 will be described by taking as an example a configuration including a solid oxide fuel cell as the fuel cell 1, but is not limited thereto.

  As shown in FIG. 1, the fuel cell system 100 includes a fuel cell 1, a reformer 2, a combustion unit 3 having an igniter 4, a power generation raw material supplier 5, an oxidant gas supplier 6, This is a configuration comprising a quality material supplier 7 and a controller 8. In the fuel cell system 100, a reforming material flow path 10, a combustible gas flow path 11, an oxidant gas flow path 12, and a combustion exhaust gas flow path 13 are provided as flow paths that connect the respective parts. .

  The power generation material supply unit 5 supplies power generation material to the reformer 2, and may be configured to adjust the flow rate of the power generation material supplied to the reformer 2. For example, the power generation raw material supplier 5 may be configured to include a booster and a flow rate adjustment valve, or may be configured to include only one of these. As the booster, for example, a constant displacement pump driven by a motor is used, but is not limited thereto. The power generation raw material is supplied from a power generation raw material supply source. Examples of the power generation raw material supply source include a gas cylinder and a gas infrastructure.

  The oxidant gas supply device 6 supplies oxidant gas to the cathode 21 of the fuel cell 1, and may be configured to be able to adjust the flow rate of oxidant gas supplied to the cathode 21 of the fuel cell 1. For example, the oxidant gas supply device 6 may be configured to include a booster and a flow rate adjustment valve, or may be configured to include only one of these. As the booster, for example, a constant displacement pump driven by a motor is used, but is not limited thereto. Examples of the oxidant gas include air in the atmosphere.

  The reforming material supplier 7 supplies the reformer 2 with water (steam) or air used for the reforming reaction, and the flow rate of water (steam) or air supplied to the reformer 2 can be adjusted. It may be configured. That is, when the reformer 2 is configured to generate a hydrogen-containing gas (reformed gas) by a steam reforming reaction, the reforming material supply unit 7 supplies water (steam) to the reformer 2 and modifies it. When the mass device 2 is configured to generate a hydrogen-containing gas by a partial oxidation reforming reaction, the reforming material supply device 7 supplies air to the reformer 2. When the reformer 2 is configured to generate a hydrogen-containing gas by an autothermal reaction, the reforming material supplier 7 supplies at least one of water (steam) and air to the reformer 2. The reforming material supply unit 7 may be configured to include a booster and a flow rate adjustment valve, or may be configured to include only one of these. As the booster, for example, a constant displacement pump driven by a motor is used, but is not limited thereto.

  The reforming material flow path 10 is a flow path from the reforming material supply device 7 to a merging portion (not shown) on the upstream side of the reformer 2 in the combustible gas flow path 11. At least one of water and air used in the reforming reaction carried out in 1 is circulated.

  The combustible gas flow path 11 is a flow path from the power generation raw material supply device 5 to the anode 20 of the fuel cell 1 through the reformer 2, and a power generation raw material or hydrogen-containing gas that is a combustible gas flows therethrough. As shown in FIG. 1, the combustible gas passage 11 corresponds to a section from the power generation raw material supplier 5 to the downstream end of the anode 20 in the fuel cell 1. That is, the combustible gas flow path 11 includes a flow path for guiding the power generation raw material from the power generation raw material supply device 5 to the reformer 2, and a hydrogen-containing gas generated by reforming the power generation raw material in the reformer 2. It is a flow path obtained by adding a flow path for guiding to the fuel cell 1.

  The oxidant gas flow path 12 is a flow path from the oxidant gas supply device 6 to the cathode 21 of the fuel cell 1, and the oxidant gas flows therethrough. As shown in FIG. 1, the oxidant gas flow path 12 corresponds to a section from the oxidant gas supply device 6 to the downstream end of the cathode 21 of the fuel cell 1.

  The fuel cell 1 generates power using the hydrogen-containing gas (reformed gas) supplied from the reformer 2 through the combustible gas flow path 11 and the oxidant gas supplied through the oxidant gas flow path 12. For example, a solid oxide fuel cell that generates electricity by reaction can be exemplified. The fuel cell 1 includes an anode 20 to which a hydrogen-containing gas is supplied and a cathode 21 to which an oxidant gas is supplied. The fuel cell 1 is a unit of a fuel cell that generates power by performing a power generation reaction between the anode 20 and the cathode 21. A plurality of cells are connected in series to form a cell stack. The fuel cell 1 may have a configuration in which cell stacks connected in series are further connected in parallel.

  As a single cell of the fuel cell constituting the fuel cell 1, for example, a single cell of a fuel cell made of zirconia doped with yttria (YSZ), zirconia doped with ytterbium or scandium, or a lanthanum gallate solid electrolyte is used. Can do. For example, when the single cell of the fuel cell is YSZ, the power generation reaction is performed in a temperature range of about 600 to 900 ° C., depending on the thickness.

  The combustion unit 3 is an area for flame-combusting hydrogen-containing gas and oxidant gas that are not used for power generation in the fuel cell 1. An igniter 4 is provided in the combustion unit 3, and the hydrogen-containing gas introduced into the combustion unit 3 is ignited by the igniter 4 and flame-combusted together with the oxidant gas. The flame combustion generates heat necessary for the fuel cell 1, the reformer 2, and the like, and generates combustion exhaust gas. The generated combustion exhaust gas is discharged out of the system through the combustion exhaust gas passage 13.

  That is, at the time of power generation of the fuel cell 1, the combustion unit 3 flame-combusts the hydrogen-containing gas discharged from the anode 20 side and the oxidant gas discharged from the cathode 21 side to generate a large amount of heat. High-temperature combustion exhaust gas is generated. The heat of the combustion exhaust gas generated by the flame combustion is used to maintain the fuel cell 1 at a temperature suitable for a power generation reaction or to heat the reformer 2 to a temperature suitable for a reforming reaction. In order to effectively use the heat of the combustion exhaust gas in this way, each of the fuel cell 1, the reformer 2, and the combustion unit 3 is housed in a so-called hot module covered with a heat insulating member. And may be housed together.

  On the other hand, the combustion exhaust gas generated in the combustion unit 3 is released out of the system through the combustion exhaust gas passage 13, but in order to effectively use the thermal energy of the high-temperature combustion exhaust gas, for example, the combustion exhaust gas passage 13 In the middle of this, a heat exchanger is provided, and the temperature of the oxidant gas is raised by heat exchange with the oxidant gas sent to the cathode 21, so that operation with a higher energy utilization rate becomes possible.

  Further, as will be described in detail later, in the fuel cell system 100, the combustible gas passage 11 is purged using the hydrogen-containing gas obtained by reforming the power generation material in the operation stop process, and the oxidizing gas is used using the oxidizing gas. Each channel 12 is purged. For this reason, when purging is performed, the hydrogen-containing gas is introduced into the combustion unit 3 from the anode side of the fuel cell 1. In this specification, the power generation raw material and the hydrogen-containing gas are collectively referred to as a combustible gas. On the other hand, an oxidant gas is introduced from the cathode 21 side of the fuel cell 1. And in the combustion part 3, the igniter 4 will ignite combustible gas and will carry out flame combustion with oxidizing agent gas.

  The reformer 2 generates a hydrogen-containing gas by a reforming reaction using a power generation raw material and at least one of water for reforming and air. Examples of the reforming reaction performed in the reformer 2 include a steam reforming reaction, an autothermal reaction, and a partial oxidation reaction as described above. The fuel cell system 100 may appropriately include necessary equipment according to the reforming reaction performed in the reformer 2. For example, when the steam reforming reaction is performed as the reforming reaction, the fuel cell system 100 may include an evaporator that generates steam and a water supplier that supplies water to the evaporator.

  The power generation raw material supplied to the fuel cell system 100 includes at least an organic compound having carbon and hydrogen as constituent elements. Specific examples of the power generation raw material include city gas mainly composed of methane, natural gas, gas containing an organic compound composed of at least carbon and hydrogen such as LPG and LNG, hydrocarbon, and alcohol such as methanol. Illustrated.

  The controller 8 controls various operations of each part of the fuel cell system 100. For example, when performing the purge in the operation stop process of the fuel cell system 100, the controller 8 depends on the elapsed time from the operation stop of the fuel cell 1, the temperature of the fuel cell 1, the temperature of the reformer 2, or the like. The power generation raw material supplier 5, the oxidant gas supplier 6, and the reforming material supplier 7 are controlled. The controller 8 adjusts the supply amount of the power generation raw material supplied to the reformer 2 and water (steam) or air, or adjusts the supply amount of the oxidant gas supplied to the fuel cell 1. .

  As a configuration for realizing such control, for example, the controller 8 may include a timer (not shown) and control the supply amounts of the power generation raw material and the oxidant gas as the predetermined time elapses. Alternatively, for example, the fuel cell 1 or the reformer 2 includes a temperature sensor (a fuel cell temperature detection unit T1, a reformer temperature detection unit T2) and the like, and the power generation raw material and the oxidant gas are detected according to the detection result by the temperature sensor. It is good also as a structure which controls each supply amount.

  Moreover, the above-mentioned controller 8 should just have a control function, and is provided with the arithmetic processing part (not shown) and the memory | storage part (not shown) which memorize | stores a control program. An MPU or CPU is exemplified as the arithmetic processing unit. Moreover, as a memory | storage part, a non-volatile memory etc. are illustrated, for example.

  The controller 8 may be composed of a single controller that performs centralized control on each part of the fuel cell system 100, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other. .

(Fuel cell system shutdown process)
Next, a specific example of the operation stop process of the fuel cell system 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing an example of the operation stop process of the fuel cell system 100 according to Embodiment 1 of the present invention. The operation shown in the flowchart can be realized, for example, when the controller 8 reads and executes a control program stored in a storage unit (not shown).

FIG. 3 is a diagram showing an example of a time-series change of each part when the fuel cell system 100 operates according to the flowchart shown in FIG. In FIG. 3, the temperature change of the reformer 2 and the fuel cell 1, the flow rate changes of the oxidant gas and the hydrogen-containing gas, and the ignition / extinguishing state change in the combustion unit 3 are shown in time series. In the graph showing the flow rate change of the hydrogen-containing gas flow rate, the purge of the combustible gas channel 11 using the hydrogen-containing gas is started at t = 0, and the combustible gas using the hydrogen-containing gas at t = t _E. It shows that the purge of the flow path 11 is finished. The flow rate of hydrogen-containing gas supplied per unit time is a constant flow rate (Q _F ) for convenience of explanation. On the other hand, the flow rate of the oxidant gas supplied per unit time is a constant flow rate (Q _o ) for convenience of explanation.

  First, when the fuel cell system 100 receives a signal for instructing operation stop (power generation stop) or determines that the operation is stopped based on a predetermined condition, the controller 8 starts an operation stop operation (step S9). The above-mentioned predetermined condition for the controller 8 to determine that the operation is stopped is, for example, when the total operation time of the fuel cell system 100 reaches a predetermined time or when the total power generation amount in the fuel cell system 100 is a predetermined power generation amount. And so on. When the controller 8 starts the operation stop operation, the power generation in the fuel cell 1 is stopped. More specifically, the controller 8 controls the power generation material supply unit 5 and the reforming material supply unit 7 so as to stop the supply of the power generation material and the reforming material (at least one of water and air). At the same time, the oxidant gas supply device 6 is controlled so as to stop the supply of the oxidant gas. In this way, the power generation of the fuel cell 1 is stopped, and the temperature of the fuel cell 1 decreases as shown in FIG.

For example, the controller 8 receives temperature information of the fuel cell 1 as a detection result from a fuel cell temperature detection unit T1 provided to detect the temperature of the fuel cell 1. Then, the controller 8 determines the magnitude relationship between the temperature of the fuel cell 1 and the predetermined temperature T _s1 (step S10).

In the fuel cell 1, a predetermined temperature T _s1 is set as a temperature within a temperature range in which water vapor contained in the hydrogen-containing gas does not condense and after a predetermined time has elapsed after the fuel cell 1 stops generating power. The predetermined temperature T _s1 can be set to 480 ° C., for example.

If the controller 8 determines that the temperature of the fuel cell 1 has decreased to T _s1 or less (“YES” in step S10), the controller 8 controls the oxidant gas supply unit 6 to oxidant gas flow path 12. The oxidant gas is supplied to the fuel cell 1 through (step S11). Next, the controller 8 controls the power generation raw material supply device 5 and the reforming material supply device 7 to cause the reformer 2 to supply the power generation raw material and the reforming material (at least one of water and air). Thereby, hydrogen-containing gas is produced | generated in the reformer 2, and this hydrogen-containing gas is supplied to the anode 20 of the fuel cell 1 through the combustible gas flow path 11 (step S12).

  That is, the oxidizing gas channel 12 is purged with the oxidizing gas. The oxidant gas purged through the oxidant gas flow path 12 is guided to the combustion unit 3 as exhaust gas. On the other hand, the combustible gas passage 11 is purged with the combustible gas. In particular, the section from the reformer 2 to the downstream end of the anode 20 of the fuel cell 1 in the combustible gas passage 11 is purged with a hydrogen-containing gas. The hydrogen-containing gas purged through the combustible gas passage 11 is guided to the combustion unit 3 as exhaust gas.

Thus, in the fuel cell system 100, the purge is started when the temperature of the fuel cell 1 becomes equal to or lower than T _s1 after power generation is stopped. In the above description, the processing in step S11 and the processing in step S12 are performed at different timings. However, the processing in step S11 and the processing in step S12 may be performed simultaneously.

Next, the controller 8 operates the igniter 4 provided in the combustion unit 3 to ignite the exhaust gas discharged from the fuel cell 1 (step S13). That is, the controller 8 ignites the hydrogen-containing gas discharged from the anode 20 of the fuel cell 1 and flame-combusts it together with the oxidant gas discharged from the cathode 21. The fuel cell 1 is heated by the heat generated by the flame combustion, and the temperature lowered to the vicinity of T _s1 gradually increases as shown in FIG. Further, the temperature of the reformer 2 also changes in conjunction with the temperature change of the fuel cell 1 as shown in FIG. 3, and the lowered temperature gradually rises.

  The hydrogen-containing gas was discharged from the anode 20 side of the fuel cell 1 to the combustion unit 3 and purged from the cathode 21 side to the combustion unit 3 by purging with the hydrogen-containing gas generated by reforming the power generation material in this way. Flame burning with oxidant gas. Thereby, it can prevent that combustible gas, such as hydrogen containing gas, is discharged | emitted in the external atmosphere through the combustion exhaust gas flow path 13 as it is. In addition, since the combustible gas passage 11 is purged not by the power generation raw material itself but by the hydrogen-containing gas obtained by reforming the power generation raw material, the power generation raw material is distributed to the reformer 2 and the fuel cell 1 in a high temperature state. In the reformer 2 and the fuel cell 1, carbon deposition can be prevented.

Next, the controller 8 determines the magnitude relationship between the total purge time (total purge time) by the hydrogen-containing gas measured by a timer (not shown) and the predetermined required purge time t _all (step S14). The required purge time t _all can be a time required to fill at least the section of the combustible gas flow path 11 from the reformer 2 to the anode of the fuel cell 1 with the hydrogen-containing gas. Further, the total purge time is a time (Σt _on ) obtained by adding the time during which the hydrogen-containing gas is supplied (purge time t _on ) as shown in FIG. In the fuel cell system 100 according to Embodiment 1, the supply time of the power generation raw material by the power generation raw material supply device 5 can be regarded as the supply time of the hydrogen-containing gas.

  That is, the fuel cell system 100 according to Embodiment 1 continuously supplies the power generation raw material and the reforming material (at least one of water and air), generates a hydrogen-containing gas, and uses the hydrogen-containing gas to generate a predetermined value. Instead of performing a purge for a period of time, it is configured to intermittently supply the power generation raw material and the reforming material and purge with the hydrogen-containing gas. This prevents the fuel cell 1 from being overheated due to the combustion heat of the hydrogen-containing gas in the combustion section 3 or suppresses the consumption of the power generation material by making the supply of the power generation material intermittent. Because. For this reason, the total purge time is the total of the purge times for the hydrogen-containing gas supplied multiple times.

As a result of the determination in step S14, when the controller 8 determines that the total purge time is not less than the required purge time t _all , that is, the required purge time has been reached (“NO” in step S14), the combustible gas channel 11 It is determined that the purging of has been completed. Therefore, in the case of “NO” in step S14, the controller 8 controls the power generation raw material supplier 5 so as to stop the supply of the power generation raw material to the combustible gas flow path 11, and the reforming material (water and water). The reforming material supplier 7 is controlled so as to stop the supply of at least one of the air. As a result, the supply of the hydrogen-containing gas to the combustible gas passage 11 is stopped (step S15). Next, the controller 8 controls the oxidant gas supply unit 6 to stop the supply of the oxidant gas to the oxidant gas flow path 12 (step S16). Then, the purge in the fuel cell system 100 is completed, and the operation stop process is ended.

  Since the water remaining in the reforming material supplier 7 evaporates in the operation stop process, the pressure on the anode 20 side becomes higher than that on the cathode 21 side, so the supply of hydrogen-containing gas is stopped as described above. Is performed before the supply of the oxidant gas is stopped, the backflow of the hydrogen-containing gas toward the cathode 21 can be prevented.

Further, the controller 8 may be configured to determine whether or not the temperature of the fuel cell 1 has become equal to or lower than a predetermined temperature _Ts2 before the above-described steps S15 and S16. When the controller 8 determines that the temperature of the fuel cell 1 has become equal to or lower than the predetermined temperature T _s2 , the above-described steps S15 and S16 may be performed. The predetermined temperature T _s2 can be set to 150 ° C. That is, when the stack temperature of the fuel cell 1 is 150 ° C. or higher in the operation stop process, if the hydrogen-containing gas is not supplied to the anode side, the oxidant gas flows backward from the downstream portion and oxidizes on the anode side. Because there is. Accordingly, it may be determined whether or not the stack temperature of the fuel cell 1 is less than 150 ° C., and when the temperature is less than 150 ° C., the supply of the hydrogen-containing gas and the oxidant gas may be stopped.

On the other hand, if the controller 8 determines that the total purge time with the hydrogen-containing gas is less than the required purge time t _all as a result of the determination in step S14 (“YES” in step S14), the process proceeds to step S17. In step S17, the controller 8 performs a comparison determination between the purge time t _on with the hydrogen-containing gas and a predetermined time (purge time t _pre-on ). The purge time t _on is the supply time of the hydrogen-containing gas per time, in other words, the supply time of the power generation raw material and the reforming material (at least one of water and air) per time.

That is, the controller 8 determines the magnitude relationship between the purge time t _on with the hydrogen-containing gas and the preset purge time t _pre-on based on the time measured by a timer (not shown). When the controller 8 determines that the purge time t _on with the hydrogen-containing gas is equal to or longer than the preset purge time t _pre-on (“YES” in step S17), the power generation material and the reforming material ( The supply of the hydrogen-containing gas is stopped by stopping the supply of water and / or air (step S18).

Here, the magnitude relationship between the purge time t _on with the hydrogen-containing gas and the preset purge time t _pre-on is determined for the following reason. That is, the fact that the purge time t _on with the hydrogen-containing gas is equal to or longer than the purge time t _pre-on set in advance means that the combustion time of the hydrogen-containing gas introduced to the combustion unit 3 is increased. Thus, if the combustion time in the combustion part 3 becomes long, the fuel cell 1 and the reformer 2 heated by the combustion heat in the combustion part 3 will overheat. If the temperature of the fuel cell 1 and the reformer 2 becomes excessively high, and the temperature of the reforming catalyst and the anode of the fuel cell 1 rises excessively, the operation time of the operation stop process becomes longer, and the power generation raw material is extra by that much. Consume. For this reason, the total power generation and fuel efficiency from the start to the stop of the fuel cell system 100 is reduced.

Therefore, in order to prevent overheating of the fuel cell 1 and the reformer 2, the purge time t _on by the hydrogen-containing gas is monitored, and when the preset purge time t _pre-on is reached, the controller 8 stops the supply of the hydrogen-containing gas.

After stopping the supply of the hydrogen-containing gas in step S18, the controller 8 performs a comparison determination between the supply stop time T _off of the hydrogen-containing gas and a predetermined time (set supply stop time t _pre-off ) (step S19). ). In other words, the controller 8 determines whether the supply stop time T _off of the hydrogen-containing gas and the preset supply stop time (set supply stop time t _pre-off ) are large or small based on the time measured by a timer (not shown). Determine the relationship. When the controller 8 determines that the supply stop time t _off of the hydrogen-containing gas is equal to or longer than the set supply stop time t _pre-off (“YES” in step S19), the supply of the hydrogen-containing gas is resumed. (Step S20).

Here, the magnitude relationship between the supply stop time t _off of the hydrogen-containing gas and the set supply stop time t _pre-off is determined for the following reason. That is, the fuel cell system 100 is configured such that the combustion exhaust gas generated in the combustion unit 3 is released to the atmosphere through the combustion exhaust gas passage 13. For this reason, when the supply of the hydrogen-containing gas is stopped for a long time, the gas in the combustible gas channel 11 contracts as the temperature of the fuel cell 1 and the reformer 2 decreases, so that the combustible gas channel 11 The air in the outside air flows in and oxidizes the reforming catalyst of the reformer 2 and the anode of the fuel cell 1. In particular, when the anode is oxidized, the durability of the fuel cell 1 is significantly reduced. Therefore, the controller 8 monitors the supply stop time t _off of the hydrogen-containing gas in order to prevent the air in the outside air from flowing into the combustible gas passage 11.

  In addition, the oxidation of the anode described above is not only an oxidation without an electrochemical reaction on the outlet side near the combustion part 3 of the combustible gas flow path 11 but also the outlet side of the anode in the high oxygen concentration state and the low oxygen concentration state. It is also caused by a local cell reaction involving an electrochemical reaction that occurs by exchange of oxide ions and electrons with the inlet side of the anode.

  Further, in the fuel cell system 100, it is not always necessary to supply a certain amount of the reforming material during the same supply period with respect to the supply of the power generation raw material. For example, when the temperature of the fuel cell 1 and the reformer 2 is lowered to a temperature at which the power generation raw material is not decomposed and carbon is deposited, the steam / carbon ratio (S / The power generation raw material feeder 5 and the reforming material supply so as to change the ratio of the respective supply amounts of the power generation raw material to be supplied and the reformed water vaporized by an evaporator (not shown) so that C) is reduced. The device 7 may be controlled. When trying to reduce S / C, the supply of reforming water is stopped below a predetermined value. For this reason, in the fuel cell system 100, the supply of the reforming water may be intermittently performed when the power generation material is supplied.

The supply stop time t _off of the hydrogen-containing gas is monitored, and when the set supply stop time t _pre-off or more is reached (“YES” in step S19), the controller 8 restarts the supply of the hydrogen-containing gas. The power generation material supplier 5 is controlled (step S20). At this time, if the temperature of the fuel cell 1 or the reformer 2 is a temperature at which the power generation raw material is not decomposed and carbon is deposited and the water vapor is not condensed, the hydrogen-containing gas supplied to the combustible gas channel 11 The controller 8 includes the power generation raw material supply unit 5 and the reforming material supply unit so as to change the ratio between the supply amount of the power generation raw material and the supply amount of the reforming water to be steamed so that the steam / carbon ratio of the steam is reduced. 7 may be controlled.

As described above, when the supply of the hydrogen-containing gas is resumed in step S20, the process returns to step S13. Then, in the determination in step S14, the processing from step S13 to step S20 is repeated until the total purge time when the hydrogen-containing gas is supplied becomes equal to or longer than the necessary purge time t _all .

  In addition, although the structure which supplies hydrogen-containing gas intermittently was demonstrated above, it is good also as a structure which supplies oxidant gas also together. In the case where the oxidizing gas is also supplied intermittently, for example, the fuel cell system 100 may be configured as follows.

  That is, after the supply of the hydrogen-containing gas is stopped in step S18 shown in FIG. 2, the controller 8 instructs the oxidant gas supply unit 6 to stop the supply of the oxidant gas. Further, after the supply of the hydrogen-containing gas is resumed in step S20, the controller 8 instructs the oxidant gas supply unit 6 to restart the supply of the oxidant gas that has been stopped. Note that the timing of stopping the supply of oxidant gas and restarting the supply of the oxidant gas may be performed after the stop of supply of the hydrogen-containing gas and the restart of supply as described above, or may be performed simultaneously.

[Modification 1 of Embodiment 1]
(Operation stop process of fuel cell system according to Modification 1)
In the above description, the purge time t _on and the supply stop time t _off by the hydrogen-containing gas are monitored and the supply and stop of the hydrogen-containing gas are controlled. However, the present invention is not limited to this. For example, as shown in FIG. 4, the temperature change of the fuel cell 1 or the reformer 2 may be monitored to control the supply and stop of the hydrogen-containing gas. FIG. 4 is a flowchart showing an example of an operation stop process of the fuel cell system 100 according to Modification 1 of Embodiment 1 of the present invention. The operation shown in the flowchart can be realized, for example, when the controller 8 reads and executes a control program stored in a storage unit (not shown).

  The flowchart of the operation stop process shown in FIG. 4 is different from the flowchart of the operation stop process shown in FIG. 2 only in the processing of step S37 and step S39, and other steps are common. For this reason, below, step S37 and step S39 are mainly demonstrated.

Is determined in step S34, if the controller 8 is determined to be less than the total purge time must purge time t _all of the hydrogen-containing gas ( "YES" in step S34), the process proceeds to step S37. In step S37, the controller 8 monitors the temperature change of the temperature of the reforming catalyst charged in the reformer 2 (reformer temperature) or the representative temperature of the fuel cell stack of the fuel cell 1 (fuel cell temperature). Then, it is determined whether or not the temperature change is within a predetermined temperature range. More specifically, the controller 8 determines whether or not the temperature (reformer rising temperature) that has risen from the temperature of the reformer 2 at the time when the exhaust gas is ignited in step S33 is equal to or higher than the rising temperature TR _-up. . Alternatively, the controller 8 determines whether or not the temperature (fuel cell rising temperature) that has risen from the temperature of the fuel cell 1 at the time when the exhaust gas is ignited in step S33 is equal to or higher than the rising temperature T _S-up .

That is, the controller 8 receives information about the temperature of the reforming catalyst (reformer temperature) from the reformer temperature detection unit T2 provided in the reformer 2, and records the history of temperature change of the reformer temperature. To do. Then, it is determined whether or not the reformer temperature at the time when the exhaust gas is ignited has risen above the preset rise temperature T _R-up of the reformer 2. Alternatively, the controller 8 receives information related to the fuel cell temperature from the fuel cell temperature detection unit T1, and records a history of the temperature change of the fuel cell temperature. Then, it is determined whether or not the temperature of the fuel cell at the time when the exhaust gas is ignited has risen by a predetermined temperature T _S-up or higher.

The fuel cell temperature changes in conjunction with the reformer temperature, and any temperature may be selected in the determination in step S37. Further, since the reformer 2 has higher responsiveness to temperature changes than the fuel cell 1, the rising temperature T _R-up of the reformer 2 is higher than the rising temperature T _{S-up of the} fuel cell 1. The width increases. For this reason, the temperature range of the rising temperature T _R-up of the reformer 2 may be set to be larger than the rising temperature T _{S-up of the} fuel cell 1.

When the controller 8 determines that the reformer rising temperature is higher than the rising temperature T _R-up or when the fuel cell rising temperature is higher than the rising temperature T _S-up (“YES” in step S37). The supply of the hydrogen-containing gas is stopped by stopping the supply of the power generation raw material and the reforming material (at least one of water and air) (step S38).

Here, the rising temperature T _R-up or the rising temperature T _S-up is set in order to prevent the reformer temperature or the fuel cell temperature from excessively rising due to heating by the combustion heat in the combustion section 3. It is.

After stopping the supply of the hydrogen-containing gas in step S38, the controller 8 determines the temperature of the reforming catalyst (reformer temperature) charged in the reformer 2 or the representative temperature of the fuel cell stack of the fuel cell 1. The temperature change of (fuel cell temperature) is monitored to determine whether or not the temperature is within a predetermined temperature range. More specifically, the controller 8 determines whether the temperature lowered from the temperature of the reformer 2 at the time when the supply of the hydrogen-containing gas is stopped in step S38 (reformer lowering temperature) is _{equal to} or higher than the lowering temperature TR _-down . Judge whether or not. Alternatively, the controller 8 determines whether or not the temperature lowered from the temperature of the fuel cell 1 when the supply of the hydrogen-containing gas is stopped in step S38 (fuel cell falling temperature) is _{equal to} or higher than the falling temperature T _S-up (step S38). S39).

That is, the controller 8 receives information on the reformer temperature from the reformer temperature detection unit T2 provided in the reformer 2, and records the history of the temperature change of the reformer temperature. Then, it is determined whether or not the reformer temperature has dropped by a preset lowering temperature TR _-down of the reformer 2 or not. Alternatively, the controller 8 receives information on the representative temperature (fuel cell temperature) of the fuel cell stack from the fuel cell temperature detection unit T1 provided in the fuel cell stack, and records the history of the temperature change of the fuel cell temperature. Then, it is determined whether or not the fuel cell temperature has decreased by a predetermined temperature T _S-down or lower. Further, as described above, the responsiveness to the temperature change is higher in the reformer 2 than in the fuel cell 1, so that the lowering temperature T _R-down of the reformer 2 is lower than the lowering temperature T of the fuel cell 1. _{Lowering range} is larger than _S-down . For this reason, the temperature range of the lowering temperature T _R-down of the reformer 2 may be set to be larger than the lowering temperature T _{S-down of the} fuel cell 1.

When the controller 8 determines that the reformer lowering temperature is equal to or higher than the lowering temperature T _R-down or the fuel cell lowering temperature is equal to or higher than the lowering temperature T _S-down (“YES” in step S39), the hydrogen-containing gas Is resumed (step S40).

In the fuel cell system according to Modification 1, the rising temperature T _R-up of the reformer 2 or the rising temperature T _S-up of the fuel cell 1 corresponds to the rising value of the present invention. On the other hand, the descending temperature T _R-down of the reformer 2 or the descending temperature T _S-down of the fuel cell 1 corresponds to the descending value of the present invention.

  As described above, in the fuel cell system 100 according to the first embodiment, the combustibility used for purging the combustible gas flow path 11 by executing the steps shown in the flowchart when the operation stop process is performed. Since the gas (hydrogen-containing gas) can be flame-combusted in the combustion unit 3, it is possible to prevent the combustible gas from being released into the atmosphere as it is. Further, since the hydrogen-containing gas obtained by reforming the power generation raw material is used for purging the combustible gas flow path 11, for example, there is a problem that carbon deposits due to the high temperature of the fuel cell 1. It can also be prevented.

  Furthermore, it is possible to prevent the temperature of the reformer 2 and the fuel cell 1 that are heated by the combustion heat in the combustion unit 3 from being excessively increased by supplying the hydrogen-containing gas intermittently. Moreover, it can also prevent that the temperature falls excessively and the water vapor | steam in the combustible gas flow path 11 condenses. Furthermore, since the supply amount of the raw material used for the purge can be suppressed by intermittently supplying the hydrogen-containing gas, it is possible to realize a reduction in energy consumption in the stop operation of the fuel cell system.

In the above, the controller 8 determines whether or not the magnitude of the temperature rise of the reformer 2 (reformer rise temperature) is equal to or higher than the rise temperature TR _-up , or the temperature rise of the fuel cell 1 (fuel cell). In this configuration, it is determined whether or not the magnitude of the rise temperature is _{equal to} or higher than the rise temperature T _{S-up and} the stop of the hydrogen-containing gas is determined. Furthermore, the controller 8 determines whether the descending temperature of the reformer 2 (reformer descending temperature) is _{equal to} or higher than the descending temperature TR _-down , or the descending temperature of the fuel cell 1 (fuel cell descending temperature). ) Is _{equal to} or lower than the descending temperature T _S-up , and the restart of the hydrogen-containing gas is determined. That is, the supply and stop of the hydrogen-containing gas are controlled according to the temperature range of the rise or fall of the reformer temperature or the fuel cell temperature.

  However, the trigger for controlling the supply and stop of the hydrogen-containing gas is not limited to the above-described temperature range of rise and fall of the reformer temperature or the fuel cell temperature. For example, the temperature profile of the reformer temperature or the fuel cell temperature may be recorded, and the supply and stop of the hydrogen-containing gas may be controlled using the magnitude of the temperature change gradient as a trigger.

[Modification 2 of Embodiment 1]
(Configuration of fuel cell system according to Modification 2)
In addition, the fuel cell system 100 may further include a desulfurizer 9 that monitors changes in the temperature of the desulfurization catalyst (desulfurizer temperature) charged in the desulfurizer 9 and controls the supply and stop of the hydrogen-containing gas. Good. Hereinafter, as a second modification of the first embodiment, refer to FIG. 5 for a configuration in which the desulfurizer temperature is monitored and the supply and stop of the hydrogen-containing gas are controlled in accordance with the temperature range of the rising temperature or the decreasing temperature of the desulfurizer temperature. To explain.

  FIG. 5 is a block diagram showing an example of a schematic configuration of the fuel cell system 100 according to Modification 2 of Embodiment 1 of the present invention.

  As shown in FIG. 5, the fuel cell system 100 according to Modification 2 further includes a desulfurizer 9 and the temperature of the desulfurization catalyst charged in the desulfurizer 9 (desulfurizer temperature) in the configuration of the fuel cell system 100 shown in FIG. 1. This is different in that a desulfurizer temperature detection unit T3 for detecting the desulfurizer and a heating unit 15 for heating the desulfurizer 9 are provided. Furthermore, it differs in that a recycle flow path 14 for supplying a part of the hydrogen-containing gas discharged from the fuel cell 1 to the desulfurizer 9 is also provided. In other respects, the configuration is the same as that of the fuel cell system 100 of the first embodiment shown in FIG.

  The desulfurizer 9 removes sulfur compounds from the power generation raw material, and examples thereof include a hydrodesulfurizer and a room temperature desulfurizer. The power generation raw material desulfurized by the desulfurizer 9 is supplied to the reformer 2. As shown in FIG. 5, the desulfurizer 9 is provided together with the heating unit 15 on the upstream side of the reformer 2 in the combustible gas flow path 11.

  When the desulfurizer 9 is a hydrodesulfurizer, when the desulfurizer is a hydrodesulfurizer, the container is filled with a hydrodesulfurizing agent. As the hydrodesulfurization agent, for example, a CuZn-based catalyst having both a function of converting a sulfur compound into hydrogen sulfide and a function of adsorbing hydrogen sulfide is used. The hydrodesulfurization agent is not limited to this example, and is a CoMo-based catalyst that converts a sulfur compound in the raw material gas into hydrogen sulfide, and a sulfur adsorbent that is provided downstream thereof to adsorb and remove hydrogen sulfide. You may comprise with a ZnO type catalyst or a CuZn type catalyst.

  In some cases, the hydrodesulfurization agent contains nickel (Ni) as a catalyst metal. In this case, if the raw material and the recycle gas are supplied to the hydrodesulfurizing agent at a low temperature (for example, less than 150 ° C.) before warming up the hydrodesulfurizer, the catalyst may deteriorate. In order to reduce this possibility, the temperature of the hydrodesulfurization agent in the desulfurizer is detected using a temperature detector (not shown), and the hydrodesulfurization agent in the desulfurizer is at a predetermined temperature or higher. Alternatively, the power generation raw material may be supplied to the hydrodesulfurizer only. When the hydrodesulfurization agent contains copper and zinc, for example, the desulfurizer has an operable range of about 150 ° C. to 350 ° C., and preferably about 250 ° C. to 320 ° C. is an appropriate operating range. When the desulfurizer is a room temperature desulfurizer, sulfur compounds in the power generation raw material can be removed at room temperature. Here, normal temperature means that the temperature is relatively close to the normal temperature range compared to the operating temperature of the hydrodesulfurizer (for example, around 300 ° C.). That is, the temperature range in which the normal temperature desulfurizer functions effectively includes the normal temperature range to the temperature range in which the desulfurizing agent functions effectively. Examples of the room temperature desulfurizer include a desulfurizer filled with an adsorptive desulfurization agent using an Ag zeolite catalyst or the like.

  As shown in FIG. 5, in the fuel cell system 100 according to the second modification, the desulfurizer is branched from the position downstream of the fuel cell 1 and upstream of the combustion unit 3 in the combustible gas passage 11. A recycling flow path 14 is provided so as to be connected to the upstream side of 9. The hydrogen necessary for hydrodesulfurization is configured such that a part of the hydrogen-containing gas generated in the reformer 2 is supplied to the desulfurizer 9 through the recycle channel 14.

  In addition, in the fuel cell system 100 according to the modified example 2, a part of the hydrogen-containing gas discharged from the fuel cell 1 is supplied to the desulfurizer 9 through the recycle channel 14, but the present invention is not limited to this. is not. For example, the recycle flow path 14 branches from a position on the downstream side of the reformer 2 and the upstream side of the fuel cell 1 in the combustible gas flow path 11, and the hydrogen-containing gas discharged from the reformer 2 A part of this may be supplied to the desulfurizer 9 through the recycling flow path 14.

  The heating unit 15 is for heating the desulfurizer 9 to a temperature suitable for desulfurization with the heat of the flue gas flowing through the flue gas passage 13, and the passage through which the flue gas flows is inside. Is formed. The combustion exhaust gas that has heated the desulfurizer 9 in the heating unit 15 is discharged out of the fuel cell system 100 through the combustion exhaust gas passage 13.

(Operation stop process of fuel cell system according to Modification 2)
Next, the operation stop process of the fuel cell system 100 according to Modification 2 will be described with reference to FIGS. FIG. 6 is a flowchart showing an example of an operation stop process of the fuel cell system 100 according to the second modification of the first embodiment of the present invention. The operation shown in the flowchart can be realized, for example, when the controller 8 reads and executes a control program stored in a storage unit (not shown).

FIG. 7 is a diagram showing an example of a time-series change of each part when the fuel cell system 100 operates according to the flowchart shown in FIG. In FIG. 7, the temperature change of the reformer 2, the fuel cell 1, and the desulfurizer 9, the change in the flow rate of the oxidant gas and the hydrogen-containing gas, and the change in the ignition / extinguishing state in the combustion unit 3 are shown in time series. ing. In the graph showing the flow rate change of the hydrogen-containing gas flow rate, the purge of the combustible gas channel 11 using the hydrogen-containing gas is started at t = 0, and the combustible gas using the hydrogen-containing gas at t = t _E. It shows that the purge in the flow path 11 is finished. The flow rate of hydrogen-containing gas supplied per unit time is a constant flow rate (Q _F ) for convenience of explanation.

The fuel cell system 100 according to Embodiment 1 is configured to monitor the purge time t _on and the supply stop time t _off by the hydrogen-containing gas and control the supply and stop of the hydrogen-containing gas. On the other hand, in the fuel cell system according to Modification 2, as shown in FIG. 6, the change in the temperature of the desulfurization catalyst (desulfurizer temperature) charged in the desulfurizer 9 is monitored, and the supply and stop of the hydrogen-containing gas is performed. It is good also as a structure which controls.

  The flowchart of the operation stop process shown in FIG. 6 is different from the flowchart of the operation stop process shown in FIG. 2 only in the processing of step S57 and step S59, and other steps are common. For this reason, below, step S57 and step S59 are mainly demonstrated.

As a result of the determination in step S54, when the controller 8 determines that the total purge time with the hydrogen-containing gas is less than the required purge time t _all (“YES” in step S54), the process proceeds to step S57. In step S57, the controller 8 monitors the temperature change of the desulfurizer temperature, and determines whether or not the temperature change is within a predetermined temperature range. More specifically, the controller 8 determines whether or not the rising temperature of the desulfurizer 9 (desulfurizer rising temperature) is equal to or higher than the rising temperature TD _-up .

That is, the controller 8 receives information on the desulfurizer temperature detected by the desulfurizer temperature detection unit T3 provided in the desulfurizer 9, and records the history of the temperature change of the desulfurizer temperature. Then, it is determined whether or not the desulfurizer temperature has risen by a preset temperature rise TD _{-up of} the desulfurizer 9 or not. As described above, the desulfurizer 9 is heated by the heat of the combustion exhaust gas through the heating unit 15. For this reason, the desulfurizer temperature changes in conjunction with the fuel cell temperature and the reformer temperature.

When the controller 8 determines that the desulfurizer rising temperature is equal to or higher than the rising temperature T _D-up (“YES” in step S57), the power generation raw material and the reforming material (at least one of water and air) The supply of the hydrogen-containing gas is stopped by stopping the supply (step S58).

Here, the rise temperature TD _-up of the desulfurizer temperature is set in order to prevent the desulfurizer temperature from being excessively increased by heating the desulfurizer 9 by the heat of the combustion exhaust gas generated in the combustion section 3. It is. In addition, since the temperature change of the desulfurizer temperature, the temperature change of the fuel cell temperature, and the temperature change of the reformer temperature are interlocked with each other, it is possible to prevent the desulfurizer temperature from rising excessively. This means that the fuel cell 1 and the reformer 2 are prevented from rising excessively.

After stopping the supply of the hydrogen-containing gas in step S58, the controller 8 monitors the temperature change of the desulfurizer temperature and determines whether it is within the predetermined temperature range. More specifically, the controller 8 determines whether or not the descending temperature of the desulfurizer 9 (desulfurizer descending temperature) is equal to or higher than the descending temperature _TD-down (step S59).

That is, the controller 8 receives information related to the desulfurizer temperature from the desulfurizer temperature detection unit T3 provided in the desulfurizer 9, and records a history of temperature change of the desulfurizer temperature. Then, it is determined whether or not the desulfurizer temperature has dropped by a preset lowering temperature TR _{-down of} the desulfurizer 9 or not. Then, when the controller 8 determines that the desulfurizer descending temperature is equal to or higher than the descending temperature _TD-down (“YES” in step S59), the supply of the hydrogen-containing gas is resumed (step S60).

In step S60, the reason for setting the descending temperature _TD-down of the desulfurizer 9 is that the temperature of the desulfurizer 9, and further the reformer 2 and the fuel cell 1 while the supply of the hydrogen-containing gas is stopped. As the temperature of the hydrogen-containing gas containing water vapor remaining in the combustible gas flow path 11 becomes lower than the dew point, water is condensed, and the durability of the catalyst and electrodes of the desulfurizer 9, the reformer 2, and the fuel cell 1 is reduced. This is to prevent the performance from significantly deteriorating.

In the fuel cell system according to Modification 2, the rising temperature T _D-up of the desulfurizer 9 and the falling temperature T _D-down of the desulfurizer 9 correspond to the rising value and the falling value of the present invention.

  As described above, in the fuel cell system 100 according to the modified example 2, the combustibility used for purging the combustible gas flow path 11 by executing the steps shown in the above-described flowchart when performing the operation stop process. Since the gas (hydrogen-containing gas) can be flame-combusted in the combustion unit 3, it is possible to prevent the combustible gas from being released into the atmosphere as it is. In addition, since the hydrogen-containing gas obtained by reforming the power generation raw material is used for purging the combustible gas flow path 11, for example, the fuel cell 1 and the reformer 2 are carbon precipitated due to high temperature. It can also prevent problems such as

  Further, the hydrogen-containing gas is intermittently supplied to prevent the desulfurizer 9, the reformer 2, and the fuel cell 1 that are heated by the heat of flame combustion in the combustion unit 3 from being overheated. can do. Moreover, it can also prevent that the temperature falls excessively and the water vapor | steam in the combustible gas flow path 11 condenses. Furthermore, since the supply amount of the raw material used for purging can be suppressed by intermittently supplying the hydrogen-containing gas, it is possible to realize reduction of energy consumption in the operation stop process of the fuel cell system 100.

In the above description, the controller 8 is configured to determine whether or not the magnitude of the rising temperature of the desulfurizer 9 (desulfurizer rising temperature) is equal to or higher than the rising temperature TD _-up , and to stop the hydrogen-containing gas. It was. Furthermore, the controller 8 is configured to determine whether or not the descending temperature of the desulfurizer 9 (desulfurizer descending temperature) is _{equal to} or higher than the descending temperature _TD-down , and determine the resumption of the hydrogen-containing gas. That is, the supply and stop of the hydrogen-containing gas are controlled according to the temperature range of the rise or fall of the desulfurizer temperature.

  However, the trigger for controlling the supply and stop of the hydrogen-containing gas is not limited to the above-described temperature range of increase and decrease of the desulfurizer temperature. For example, the temperature profile of the desulfurizer temperature may be recorded, and the supply and stop of the hydrogen-containing gas may be controlled by using the magnitude of the temperature change slope as a trigger.

[Modification 3 of Embodiment 1]
(Configuration of fuel cell system according to Modification 3)
Next, the configuration of the fuel cell system 100 according to Modification 3 of Embodiment 1 of the present invention will be described with reference to FIG. FIG. 8 is a block diagram showing an example of a schematic configuration of a fuel cell system 100 according to Modification 3 of Embodiment 1 of the present invention.

  The fuel cell system 100 according to Modification 3 further includes a purifier 16 and a purifier temperature detection unit T4 that detects the temperature of the purifier 16 in the configuration of the fuel cell system 100 according to Modification 2 shown in FIG. It has a configuration with. In other respects, the configuration is the same as that of the fuel cell system 100 according to Modification 2 shown in FIG. 5, and thus the same members are denoted by the same reference numerals and description thereof is omitted.

  The purifier 16 removes combustible gas contained in the combustion exhaust gas discharged from the combustion unit 3. For example, the purifier 16 purifies hydrocarbons such as carbon monoxide, nitrogen oxides and residual methane contained in the combustion exhaust gas into carbon dioxide, nitrogen dioxide and water vapor (water). As shown in FIG. 8, the purifier 16 is provided in the combustion exhaust gas passage 13 on the downstream side of the heating unit 15 that heats the desulfurizer 9.

  As a purification catalyst with which the purifier 16 is filled, for example, a container is filled with a combustion catalyst and an exhaust gas purification catalyst. As the combustion catalyst and the exhaust gas purification catalyst, for example, an alumina carrier impregnated with at least one of platinum, palladium, and rhodium, or a metal carrier can be used. The combustion catalyst and the exhaust gas purification catalyst are not limited to these, and may be any catalyst that can advance the combustion reaction and the purification reaction when maintained in the optimum temperature range. The combustion reaction and the purification reaction refer to a reaction for purifying unburned combustible gas such as hydrocarbon, hydrogen, carbon monoxide, and nitrogen oxide contained in the gas flowing through the combustion exhaust gas passage 13. In the case of the Pd—Al 2 O 3 purification catalyst, the purifier 16 removes the combustible gas in the combustion exhaust gas at a predetermined temperature (eg, 130 ° C.) or higher. However, if the temperature is too high, the catalytic activity decreases due to aggregation of Pd or the like, so it is desirable to maintain a predetermined temperature (for example, 300 ° C.) or lower.

  The purifier 16 is configured to heat the desulfurizer 9 by the heating unit 15 and to be heated by the combustion exhaust gas that has lost some of the heat it has. When the purifier 16 is heated by the heat of the combustion exhaust gas as described above, the purifier 16 is provided at a position close to the desulfurizer 9 so that the heat of the combustion exhaust gas can be used more effectively. Also good. The combustion exhaust gas that has passed through the purifier 16 is discharged out of the fuel cell system 100 in a state where the combustible gas is purified while heating the purifier 16 as described above.

(Operation stop process of fuel cell system according to Modification 3)
Next, the operation stop process of the fuel cell system 100 according to Modification 3 will be described below with reference to FIG. FIG. 9 is a flowchart showing an example of the operation stop process of the fuel cell system 100 according to Modification 3 of Embodiment 1 of the present invention. The operation shown in the flowchart can be realized, for example, when the controller 8 reads and executes a control program stored in a storage unit (not shown).

In the fuel cell system 100 according to the first embodiment, as shown in FIG. 2, the oxidant gas is supplied (step S11), and the hydrogen-containing gas is supplied (step S12). The exhaust gas discharged is ignited (step S13). In contrast, in the fuel cell system 100 according to Modification 3, after the hydrogen-containing gas is supplied, the temperature of the purifier 16 determines whether the predetermined temperature T _puri above, when less than the predetermined temperature T _puri The only difference is that the igniter 4 is configured to ignite the exhaust gas. That is, only step S73 in FIG. 9 is newly added, and other steps S70 to 72 and 74 to 81 are common to steps S10 to 20 in FIG. For this reason, below, step S73 is mainly demonstrated.

When the oxidizing gas is supplied to the oxidizing gas channel 12 in step S71 and the hydrogen-containing gas is supplied to the combustible gas channel 11 in step S72, the controller 8 monitors the temperature change of the purifier 16. To do. Specifically, the controller 8 receives information on the temperature (purifier temperature) of the purification catalyst charged in the purifier 16 detected by the purifier temperature detection unit T4 provided in the purifier 16, and this purification. The magnitude relationship between the vessel temperature and the predetermined temperature T _puri is determined (step S73). Here, the predetermined temperature T _puri is a lower limit temperature of the temperature range in which the purification catalyst is activated. In the case of a Pd—Al 2 O 3 purification catalyst, the predetermined temperature T _puri is about 130 ° C. Therefore, when the controller 8 determines that the purifier temperature is equal to or higher than the predetermined temperature T _puri (“YES” in step S73), the purifier 16 can purify the combustible gas contained in the combustion exhaust gas. It is in. On the other hand, when the controller 8 determines that the purifier temperature is _lower than the predetermined temperature T _puri (“NO” in step S73), the purifying catalyst is not activated and is included in the combustion exhaust gas in the purifier 16. It is in a state where the combustible gas to be removed cannot be removed.

Incidentally, as described above, the purifier 16 is configured to be heated by the heat of the combustion exhaust gas. For this reason, for example, before the state in which the hydrogen-containing gas is burned by the igniter 4 in the combustion unit 3, the purifier temperature is less than the predetermined temperature T _puri .

As described above, when the purifier temperature is _lower than the predetermined temperature T _puri , the controller 8 controls the igniter 4 to ignite the exhaust gas (combustible gas) discharged from the fuel cell 1 (step S74). On the contrary, when the purifier 16 is heated by the heat of the combustion exhaust gas generated in the combustion unit 3 and the purifier temperature becomes _{equal to} or higher than the predetermined temperature T _puri , the operation of the igniter 4 is stopped, and the purifier 16 causes the combustible gas. To purify.

As described above, in the fuel cell system 100 according to the modified example 3, while the purifier temperature is _lower than the predetermined temperature T _puri and the purifying catalyst is not activated, the controller 8 causes the ignition unit 4 to be connected to the combustion unit 3. A flammable gas is burned by controlling and igniting. On the other hand, when the purifier 16 is heated and the purifier temperature becomes _{equal to} or higher than the predetermined temperature T _puri , the purifier 16 is configured to purify the combustible gas. For this reason, in the fuel cell system 100 according to the modified example 3, the purifier 16 can purify the combustible gas at a temperature lower than that of the combustion unit 3.

  Therefore, in the fuel cell system 100 according to the third modification, the purifier 16 that can purify the combustible gas at a temperature lower than that of the combustion unit 3 and the combustion of the combustible gas by the combustion unit 3 are combined to make combustibility. The amount of heat required for gas purification can be suppressed. Therefore, the temperature of the fuel cell system 100 can be more efficiently lowered as compared with the configuration in which the combustible gas is purified only by the combustion unit 3.

[Modification 4 of Embodiment 1]
In the fuel cell system 100 according to the first embodiment described above, as shown in FIG. 2, the hydrogen-containing gas is supplied and stopped based on the purge time for the combustible gas flow path 11 with the hydrogen-containing gas, or the shutdown process is performed. It was the composition which decided the end. In addition, when supplying the hydrogen-containing gas, the hydrogen-containing gas discharged from the fuel cell 1 in the combustion unit 3 is flame-combusted together with the oxidant gas supplied to the oxidant gas flow path 12. .

  In the case of the fuel cell system 100 configured to intermittently supply the hydrogen-containing gas and purge the combustible gas flow path 11 as described above, the fuel cell 1 is compared with the fuel cell system configured not to purge at all. The time required for cooling to a predetermined temperature or lower, in other words, the time required for the operation stop process becomes longer. Therefore, in the fuel cell system according to Modification 4 of Embodiment 1, the fuel cell system 100 having the configuration shown in FIG. 1 operates as shown below so that the time required for the operation stop process can be reduced as much as possible. A stop process is performed.

  Note that, similarly to the fuel cell system 100 according to Modification Example 2, the fuel cell system 100 according to Modification Example 4 controls the supply and stop of the hydrogen-containing gas in accordance with the temperature range of the increase or decrease in the fuel cell temperature. For this reason, it can be said that the fuel cell system 100 according to the modification 4 is an aspect of the fuel cell system 100 according to the modification 2. In the fuel cell system 100 according to the modified example 4, the temperature rise range of the fuel cell 1 for determining the supply stop of the hydrogen-containing gas and the resumption of supply of the hydrogen-containing gas are determined so that the time required for the operation stop process can be reduced. In this configuration, the relationship with the temperature drop of the fuel cell 1 is further considered.

(Operation stop process of fuel cell system according to Modification 4)
Hereinafter, the operation stop process of the fuel cell system 100 according to Modification 4 will be described with reference to FIGS. 10 and 11. FIG. 10 is a flowchart showing an example of the operation stop process of the fuel cell system 100 according to Modification 4 of Embodiment 1 of the present invention. The operation shown in the flowchart can be realized, for example, when the controller 8 reads and executes a control program stored in a storage unit (not shown).

FIG. 11 is a diagram showing an example of a time-series change of each part when the fuel cell system 100 operates according to the flowchart shown in FIG. In FIG. 11, the temperature change of the fuel cell 1, the state change of ignition / extinguishing in the combustion section 3, and the flow rates of the supplied oxidant gas and hydrogen-containing gas are shown in time series. In the graph showing the change in the flow rate of the hydrogen-containing gas, the purge in the combustible gas channel 11 using the hydrogen-containing gas is started at t = 0. The flow rate of the hydrogen-containing gas supplied per unit time is a constant flow rate (Q _F ) for convenience of explanation. On the other hand, the flow rate of the oxidant gas supplied per unit time is a constant flow rate (Q _O ) for convenience of explanation.

  The flowchart of the operation stop process shown in FIG. 10 differs from the operation stop process flowchart shown in FIG. 2 only in the processes of steps S94, S97, and S99, and other steps (steps S90 to S93, steps S95 to S96, S98, and S100). ) Is common to steps S10 to S13, steps S15 to S16, S18, and S20 shown in FIG. For this reason, below, step S94, S97, and S99 are mainly demonstrated.

  When the exhaust gas is ignited by the igniter 4 in step S93, the combustion exhaust gas generated in the combustion unit 3 flows through the combustion exhaust gas passage 13, and the fuel cell 1 and the reformer 2 are heated by the heat accompanying combustion in the combustion unit 3. Etc. are also heated. For this reason, the temperature of the fuel cell 1 gradually rises as shown in FIG.

In the next step S94, the controller 8 performs a comparison determination between the fuel cell temperature of the fuel cell 1 and a predetermined temperature (fuel cell temperature T _S2 ). That is, the controller 8 receives information on the fuel cell temperature detected by the fuel cell temperature detector T1 provided in the fuel cell stack, and the magnitude relationship between the fuel cell temperature and the preset fuel cell temperature T _S2. Determine. Note that the fuel cell temperature T _S2 is a temperature that serves as a standard for ending the operation stop process, and can be set to about 150 ° C., for example. That is, when the stack temperature of the fuel cell 1 is 150 ° C. or higher in the operation stop process, if the hydrogen-containing gas is not supplied to the anode side, the oxidant gas flows backward from the downstream portion and oxidizes on the anode side. Because there is.

Therefore, the controller 8 determines whether or not the fuel cell temperature is equal to or higher than a preset fuel cell temperature T _S2 (= 150 ° C.) (step S94). If the temperature is lower than 150 ° C. (“NO” in step S94). ]), The supply of the hydrogen-containing gas and the oxidant gas is stopped (steps S95 and S96).

On the other hand, if “YES” in the step S94, the controller 8 records the fuel cell temperature detected at the time of the determination in the step S94 in a memory (not shown). Then, the controller 8 determines whether or not the temperature increased from the fuel cell temperature at the time of recording in the memory is equal to or higher than a predetermined increased temperature T _S-up (step S97). Here, the predetermined rising temperature T _S-up can be set to 1 ° C. as shown in FIG. 11, for example. Further, the fuel cell temperature at the time of recording in the memory can be the fuel cell temperature at the time when the exhaust gas is ignited by the igniter 4.

When the controller 8 determines in step S97 that the fuel cell rising temperature is equal to or higher than the rising temperature T _S-up (“YES” in step S97), the supply of the hydrogen-containing gas to the combustible gas passage 11 is stopped ( Step S98). Thus, when the supply of the hydrogen-containing gas is stopped, the flame combustion of the exhaust gas in the combustion unit 3 is also stopped, and the temperature of the fuel cell 1, the reformer 2, etc. in the fuel cell system 100 is also lowered. Further, the controller 8 records the fuel cell temperature at the time when the supply of the hydrogen-containing gas is stopped in a memory (not shown). Then, the controller 8 monitors the change in the fuel cell temperature.

Next, the controller 8 refers to the fuel cell temperature recorded in the memory, and the temperature lowered from the temperature of the fuel cell 1 at the time when the supply of the hydrogen-containing gas is stopped is a predetermined lowered temperature T _S-down. It is determined whether or not this is the case (step S99). Here, when the controller 8 determines that the fuel cell lowering temperature is equal to or higher than the lowering temperature T _S-down (“YES” in step S99), the supply of the hydrogen-containing gas to the combustible gas passage 11 is resumed. Further, the controller 8 restarts the supply of the hydrogen-containing gas, and records the fuel cell temperature at the time when the exhaust gas is ignited in a memory (not shown).

Here, the speed of temperature decrease of the fuel cell 1, the reformer 2, etc. in the fuel cell system 100 is determined depending on how much the predetermined descending temperature T _S-down is set. That is, if the temperature range of the descending temperature T _S-down is made as large as possible, the time required for temperature reduction of the fuel cell 1, the reformer 2, etc. is reduced, but the period for stopping the supply of the hydrogen-containing gas is lengthened. In some cases, the oxidant gas flows backward from the downstream side on the anode side of the fuel cell 1 and the anode is oxidized. Therefore, the lowering temperature T _S-down is set to be as high as possible within a range in which the anode of the fuel cell 1 is not oxidized. For example, in the fuel cell system 100 according to the modified example 4, as shown in FIG. 11, the descending temperature T _S-down can be set to 10 ° C.

Above the fuel cell temperature is lowered the temperature T _S-down above, each time decreases, increasing the temperature T _{S-Stay up-above,} by the structure for implementing the purge with a hydrogen-containing gas to rise, the fuel cell system 100 The anode can be prevented from being oxidized by purging with the hydrogen-containing gas in the combustible gas passage 11 while cooling the gas efficiently. In particular, the cooling rate of the fuel cell system 100 can be adjusted to a desired rate by appropriately setting the relationship between the temperature _{ranges of the} descending temperature T _S-down and the increasing temperature T _S-up .

  In the operation stop process shown in FIG. 10, the fuel cell system 100 has decided to stop and restart the supply of the hydrogen-containing gas based on the temperature change of the fuel cell temperature, but the present invention is not limited to this. For example, the supply stop and restart of the hydrogen-containing gas may be determined based on the temperature change of the reformer temperature that changes in conjunction with the fuel cell temperature. As described above, when the fuel cell system 100 according to the modified example 4 is configured so that the supply of hydrogen is stopped and restarted based on the temperature change of the reformer temperature, the controller 8 is configured as shown in FIG. Steps S94, S97, and S99 shown in FIG.

  That is, when the exhaust gas is ignited by the igniter 4 in step S93, the combustion exhaust gas generated in the combustion section 3 flows through the combustion exhaust gas flow path 13, and the fuel cell 1, reforming is performed by the heat accompanying combustion in the combustion section 3. The vessel 2 and the like are also heated. For this reason, the temperature of the reformer 2 gradually increases in conjunction with the temperature of the fuel cell 1.

Next, in step S94, the controller 8 performs a comparison determination between the reformer temperature and a predetermined temperature (reformer temperature T _R2 ). That is, the controller 8 receives information on the reformer temperature detected by the reformer temperature detection unit T2 provided in the reformer 2, and the reformer temperature and the preset reformer temperature T are received. Determine the magnitude relationship with _R2 .

In the fuel cell system 100, the reformer 2 is configured to be heated by the heat of flame combustion in the combustion unit 3 as in the fuel cell 1. Therefore, since the reformer temperature and the fuel cell temperature are similar, the reformer temperature T _R2 can be set to about 150 ° C., for example, similarly to the fuel cell temperature T _S2 .

Then, the controller 8 determines whether or not the reformer temperature is equal to or higher than a preset reformer temperature T _R2 (= 150 ° C.). If the reformer temperature is lower than 150 ° C., the hydrogen-containing gas and the oxidant gas are determined. Is stopped (steps S95 and S96).

On the other hand, when the controller 8 determines that the reformer temperature is equal to or higher than the reformer temperature T _R2 (about 150 ° C.), the reformer temperature detected at the time of this determination is recorded in a memory (not shown). Then, the controller 8 determines whether or not the temperature increased from the reformer temperature at the time of recording in the memory is _{equal to} or higher than a predetermined increased temperature TR _-up . Here, the predetermined rising temperature T _R-up can be set to 1 ° C., for example, similarly to the rising temperature T _S-up . Alternatively, the temperature rise T _R-up may be a temperature higher than 1 ° C. because the reformer 2 has higher responsiveness to temperature changes than the fuel cell 1.

When the controller 8 determines that the reformer rising temperature is _{equal to} or higher than the rising temperature T _R-up , the supply of the hydrogen-containing gas to the combustible gas passage 11 is stopped. When the supply of the hydrogen-containing gas is stopped in this way, the flame combustion of the exhaust gas in the combustion unit 3 is also stopped, and the temperature of the fuel cell 1, the reformer 2, etc. in the fuel cell system 100 is also lowered. Therefore, the controller 8 records the reformer temperature at the time of stopping the supply of the hydrogen-containing gas in a memory (not shown), and monitors the change in the reformer temperature.

Next, the controller 8 refers to the fuel cell temperature recorded in the memory, and the temperature lowered from the temperature of the reformer 2 at the time when the supply of the hydrogen-containing gas is stopped is a predetermined lowered temperature T _{R−. Judge} whether it is more than _down . Here, when the controller 8 determines that the reformer lowering temperature is equal to or higher than the lowering temperature TR _-down , the supply of the hydrogen-containing gas to the combustible gas passage 11 is restarted. Further, the controller 8 restarts the supply of the hydrogen-containing gas, and records the reformer temperature at the time when the exhaust gas is ignited in a memory (not shown). The lowering temperature T _R-down of the reformer 2 is set to be as high as possible within a range in which the anode of the fuel cell 1 does not oxidize. For example, the lowering temperature T _{S of the} fuel cell 1 It can be about 10 _degreeC like _-down . Alternatively, the lowering temperature T _R-down may be a temperature higher than 10 ° C. because the reformer 2 is more responsive to temperature changes than the fuel cell 1.

As described above, every time the reformer temperature decreases by the lowering temperature T _R-down or more, the purge with the hydrogen-containing gas is performed until the temperature rises by the rising temperature T _R-up or more. The anode can be prevented from being oxidized by purging with the hydrogen-containing gas in the combustible gas passage 11 while cooling the gas efficiently.

  In the fuel cell system 100 according to the modified example 4, the temperature of the fuel cell 1 or the reformer 2 is taken into consideration, and the purge timing with the hydrogen-containing gas that is intermittently performed is determined. In consideration, the timing of the purge with the hydrogen-containing gas that is intermittently performed can also be determined. Hereinafter, a configuration in which purging with a hydrogen-containing gas is intermittently performed in consideration of a change in pressure in the combustible gas passage 11 will be referred to as a modified example 5, and hydrogen content is intermittently considered in consideration of a change in voltage in the fuel cell 1. A configuration for purging with gas will be described as a sixth modification.

[Modification 5 of Embodiment 1]
A fuel cell system 100 according to Modification 5 of Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 12 is a block diagram showing an example of a schematic configuration of a fuel cell system 100 according to Modification 5 of Embodiment 1 of the present invention. FIG. 13 is a flowchart showing an example of the operation stop process of the fuel cell system 100 according to Modification 5 of Embodiment 1 of the present invention. FIG. 14 is a diagram showing an example of a time-series change of each part when the fuel cell system 100 operates according to the flowchart shown in FIG. In FIG. 14, the pressure change in the combustible gas flow path 11, the ignition / extinguishing state change in the combustion unit 3, and the supplied hydrogen-containing gas flow rate are shown in time series. Further, in the graph showing the flow rate change of the hydrogen-containing gas flow rate, the purge in the combustible gas channel 11 using the hydrogen-containing gas is started at t = 0. The flow rate of hydrogen-containing gas supplied per unit time is a constant flow rate (Q _F ) for convenience of explanation. In addition, the pressure of the combustible gas passage 11 that changes in accordance with the supply of the hydrogen-containing gas is set to a constant pressure (N) for convenience of explanation.

(Configuration of fuel cell system according to Modification 5)
As shown in FIG. 12, the fuel cell system 100 according to the modified example 5 is configured to further include a pressure sensor P that detects the pressure of the combustible gas passage 11 in the configuration of the fuel cell system 100 shown in FIG. 1. . Since other members are the same as those of the fuel cell system 100 shown in FIG. 1, the same members are denoted by the same reference numerals, and description thereof is omitted.

  The pressure sensor P is provided on the upstream side of the reformer 2 in the combustible gas channel 11 and detects the pressure in the combustible gas channel 11. The pressure sensor P detects a pressure change in the combustible gas flow path 11 accompanying the supply of the power generation raw material, and regards this pressure change as a pressure change in the combustible gas flow path 11. The pressure change in the combustible gas passage 11 is proportional to the supply amount of the hydrogen-containing gas, in other words, the supply amount of the power generation raw material, as shown in FIG.

(Operation stop process in fuel cell system according to Modification 5)
An operation stop process of the fuel cell system according to Modification 5 having the above-described configuration will be described with reference to FIG.

  The operation stop process shown in FIG. 13 is different from the operation stop process shown in FIG. 10 only in steps S117 and S119, and other steps (steps S110 to S116, S118, and S120) are steps shown in FIG. Common to S90 to S96, S98, and S100. For this reason, steps S117 and S119 will be mainly described below.

When the exhaust gas is ignited by the igniter 4 in step S113, the combustion exhaust gas generated in the combustion unit 3 flows through the combustion exhaust gas passage 13, and the fuel cell 1 and the reformer 2 are heated by the heat accompanying combustion in the combustion unit 3. Etc. are also heated. In the next step S114, the controller 8 receives information on the fuel cell temperature detected by the fuel cell temperature detector T1 provided in the fuel cell stack, and this fuel cell temperature and a preset fuel cell temperature T. Determine the magnitude relationship with _S2 . Note that the fuel cell temperature T _S2 is a temperature that serves as a standard for ending the operation stop process, and can be set to about 150 ° C., for example. The controller 8 determines whether or not the fuel cell temperature is equal to or higher than a preset fuel cell temperature T _S2 (= 150 ° C.). If the temperature is lower than 150 ° C. (“NO” in step S114), the hydrogen-containing gas Then, the supply of the oxidant gas is stopped (steps S115 and S116).

On the other hand, if “YES” in step S <b> 114, the controller 8 receives information related to the pressure of the combustible gas passage 11 from the pressure sensor P and determines the magnitude relationship with the predetermined pressure N. The predetermined pressure N is the pressure of the combustible gas passage 11 or the pressure in the vicinity thereof when the hydrogen-containing gas having a flow rate Q (F) per unit time flows. Furthermore, the controller 8 determines the magnitude relationship between the purge time t _on with the hydrogen-containing gas and a preset purge time t _pre-on based on the time measured by a timer (not shown).

When the controller 8 determines that the pressure in the combustible gas passage 11 is equal to or higher than the predetermined pressure N and the purge time t _on with the hydrogen-containing gas is equal to or longer than a preset purge time t _pre-on ( In Step S117, “YES”), the supply of the hydrogen-containing gas is stopped by stopping the supply of the power generation raw material and the reforming material (at least one of water and air) (Step S118).

After stopping the supply of the hydrogen-containing gas in step S118, the controller 8 receives information related to the pressure of the combustible gas passage 11 from the pressure sensor P, and determines the magnitude relationship with the atmospheric pressure. Further, the controller 8 makes a comparison determination between the supply stop time T _off of the hydrogen-containing gas and a predetermined time (set supply stop time t _pre-off ) (step S119). When the controller 8 determines that the pressure in the combustible gas passage 11 is equal to or lower than the atmospheric pressure and the supply stop time t _off of the hydrogen-containing gas is equal to or longer than the set supply stop time t _pre-off (in step S119). “YES”), the supply of the hydrogen-containing gas is resumed (step S120). In addition, although it is the structure which determines the magnitude relationship between the pressure of the combustible gas flow path 11 and atmospheric pressure in step S119, the predetermined pressure slightly higher than atmospheric pressure and the pressure of the combustible gas flow path 11 are compared. It may be a configuration. That is, any configuration may be used as long as it can be monitored so that the inside of the combustible gas passage 11 does not become negative pressure.

Here, the determination of the magnitude relationship between the purge time t _on and the purge time t _pre-on by the hydrogen-containing gas, and the judgment of the magnitude relationship between the supply stop time t _off of the hydrogen-containing gas and the set supply stop time t _pre-off. In addition, the determination of the magnitude relationship between the pressure of the combustible gas passage 11 and the predetermined pressure N and the judgment of the magnitude relationship between the pressure of the combustible gas passage 11 and the atmospheric pressure are performed for the following reasons. is there.

In the operation stop process of the fuel cell system 100, first, the power generation in the fuel cell 1 is stopped by starting the operation stop operation in step S109, and the temperatures of the fuel cell 1, the reformer 2, and the like are lowered. As the temperature decreases, the residual gas in the combustible gas flow path 11 contracts to reduce the pressure. Furthermore, when the water vapor contained in the residual gas in the combustible gas channel 11 reaches the dew point and condenses, the pressure in the combustible gas channel 11 decreases. As a result, when the pressure of the combustible gas passage 11 becomes negative, air flows from the outside and the anode side is oxidized. Therefore, in the fuel cell system 100 according to the modified example 5, in order to prevent oxidation of the anode, the hydrogen-containing gas is supplied to compensate for the reduced pressure when the inside of the combustible gas flow path 11 becomes the atmospheric pressure or lower, The combustible gas flow path 11 is prevented from becoming a negative pressure. On the contrary, when the purge time t _on is equal to or longer than the preset purge time t _pre-on and the pressure in the combustible gas flow path 11 is equal to or higher than the predetermined pressure N, that is, not negative, the hydrogen-containing gas Can be stopped.

[Modification 6 of Embodiment 1]
A fuel cell system 100 according to Modification 6 of Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 15 is a block diagram showing an example of a schematic configuration of a fuel cell system 100 according to Modification 6 of Embodiment 1 of the present invention. FIG. 16 is a flowchart showing an example of the operation stop process of the fuel cell system 100 according to Modification 6 of Embodiment 1 of the present invention. FIG. 17 is a diagram showing an example of a time-series change of each part when the fuel cell system 100 operates according to the flowchart shown in FIG. In FIG. 17, the change in the single cell average voltage of the fuel cell 1, the change in the ignition / extinguishing state in the combustion section 3, and the flow rates of the supplied oxidant gas and hydrogen-containing gas are shown in time series. In the graph showing the change in the flow rate of the hydrogen-containing gas, the purge in the combustible gas channel 11 using the hydrogen-containing gas is started at t = 0. The flow rate of the hydrogen-containing gas supplied per unit time is a constant flow rate (Q _F ) for convenience of explanation.

(Configuration of fuel cell system according to Modification 6)
As shown in FIG. 15, the fuel cell system 100 according to the modified example 6 has a configuration further including a voltage detector V that detects the voltage of the fuel cell 1 in the configuration of the fuel cell system 100 shown in FIG. 1. Since other members are the same as those of the fuel cell system 100 shown in FIG. 1, the same members are denoted by the same reference numerals, and description thereof is omitted.

  The voltage detector V detects the voltage of the fuel cell 1. Specifically, the voltage detector V detects the average value of the voltage of a predetermined single cell in the cell stack of the fuel cell 1 as the voltage of the fuel cell 1.

  Incidentally, in the operation stop process, when the operation stop operation of step S129 shown in FIG. 16 is started, the power generation in the fuel cell 1 is stopped. For this reason, after the operation stop operation is started, the voltage detector V does not detect a voltage change accompanying power generation. However, when the temperature of the fuel cell 1 and the reformer 2 is decreased after the operation is stopped, the pressure of the combustible gas flow path 11 is decreased as described above, and air may flow into the anode. In such a case, a voltage drop is caused in the single cell of the fuel cell 1. That is, the voltage change in the single cell of the fuel cell 1 can be used as a guideline for determining whether air flows into the anode.

  Therefore, in the fuel cell system 100 according to the modified example 6, when the voltage of the fuel cell 1 is decreased, the hydrogen-containing gas is supplied to prevent the air from flowing in on the anode side.

(Operation stop process in fuel cell system according to Modification 6)
An operation stop process of the fuel cell system 100 according to Modification 6 having the above-described configuration will be described with reference to FIG.

  The operation stop process shown in FIG. 16 is different from the operation stop process shown in FIG. 10 only in steps S137 and S139, and the other steps (steps S130 to S136, S138, and S140) are the steps shown in FIG. Common to S90 to S96, S98, and S100. For this reason, steps S137 and S139 will be mainly described below.

When the exhaust gas is ignited by the igniter 4 in step S133, the combustion exhaust gas generated in the combustion section 3 flows through the combustion exhaust gas flow path 13, and the fuel cell 1 and the reformer are heated by the heat accompanying flame combustion in the combustion section 3. 2 etc. are also heated. In the next step S134, the controller 8 receives information on the fuel cell temperature from the fuel cell temperature detector T1, and determines the magnitude relationship between the fuel cell temperature and a preset fuel cell temperature T _S2 . Note that the fuel cell temperature T _S2 is a temperature that serves as a standard for ending the operation stop process, and can be set to about 150 ° C., for example. The controller 8 determines whether or not the fuel cell temperature is equal to or higher than a preset fuel cell temperature T _S2 (= 150 ° C.). If the temperature is lower than 150 ° C. (“NO” in step S134), the hydrogen-containing gas Then, the supply of the oxidant gas is stopped (steps S135 and S136).

On the other hand, if "YES" in step S134, the controller 8 receives information about the voltage of the fuel cell 1 from the voltage detector V, it determines the size relationship between the predetermined voltage V _1. The predetermined voltages V _1, the air from the outside is the voltage of the fuel cell 1 during state not flowing through the combustion gas passage 13 to the combustible gas channel 11, for example, be a 0.75V .

When the controller 8 determines that the voltage of the fuel cell 1 is equal to or higher than the predetermined voltage V ₁ (“YES” in step S134), the power generation raw material and the reforming material (at least one of water and air) The supply of hydrogen-containing gas is stopped by stopping the supply of (Step S138).

After stopping the supply of hydrogen-containing gas at step S138, the controller 8 receives information about the voltage of the fuel cell 1 from the voltage detector V, it determines the size relationship between the predetermined voltage V ₂ (step S139). Then, the controller 8, ( "YES" in step S139) when the voltage of the fuel cell 1 is determined to be a predetermined voltage _{V 2} or less, resume the supply of hydrogen-containing gas (step S140). The predetermined voltage V ₂ is at a voltage of the fuel cell 1 at the time a state in which air from the outside through the flue gas passage 13 to the combustible gas channel 11 flows into, i.e. combustible gas channel 11 becomes a negative pressure For example, it can be 0.65V.

  Modifications 4 to 6 are configured to determine whether to stop the supply of hydrogen-containing gas and restart the supply in consideration of changes in the fuel cell temperature, changes in the pressure of the combustible gas flow path 11, or changes in the voltage of the fuel cell 1, respectively. there were. However, the present invention is not limited to these configurations, and after considering changes in the fuel cell temperature, changes in the pressure of the combustible gas flow path 11, or changes in the voltage of the fuel cell 1, the fuel cell temperature and reformer temperature are further increased. Or it is good also as a structure which determines the magnitude relationship between desulfurizer temperature and predetermined temperature, and determines the supply stop and supply restart of hydrogen-containing gas.

[Embodiment 2]
(Configuration of fuel cell system)
First, the configuration of the fuel cell system 200 according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 18 is a block diagram showing an example of a schematic configuration of a fuel cell system 200 according to Embodiment 2 of the present invention. The fuel cell system 200 will be described by taking as an example a configuration including a solid oxide fuel cell as the fuel cell 201, but is not limited thereto.

  As shown in FIG. 18, the fuel cell system 200 includes a fuel cell 201, a reformer 202, an evaporator 203, a heater 204, a power generation raw material supplier 205, an oxidant gas supplier 206, and a memory. The apparatus 207 includes a device 207, a controller 208, a reforming water supplier 209 as a reforming material supplier, and a combustion unit 210. In the fuel cell system 200, a combustible gas channel 211, an oxidant gas channel 212, and a reforming water channel 213 are provided as channels that connect the respective parts.

  The power generation material supply unit 205 supplies power generation material to the reformer 202 and may be configured to be able to adjust the flow rate of the power generation material supplied to the reformer 202. Since the power generation material supply unit 205 has the same configuration as that of the power generation material supply unit 5 included in the fuel cell system 100 according to Embodiment 1, detailed description thereof is omitted.

  The oxidant gas supply unit 206 supplies oxidant gas to the cathode 221 of the fuel cell 201, and may be configured to be able to adjust the flow rate of oxidant gas supplied to the cathode 221 of the fuel cell 201. Since the oxidant gas supply unit 206 has the same configuration as that of the oxidant gas supply unit 6 included in the fuel cell system 100 according to Embodiment 1, detailed description thereof is omitted.

  The reforming water supply unit 209 supplies water (steam) used for the reforming reaction to the reformer 202, and is configured to be able to adjust the flow rate of water (steam) supplied to the reformer 202. It may be. The reforming water supplier 209 may be configured to include a booster and a flow rate adjustment valve, or may be configured to include only one of these. As the booster, for example, a constant displacement pump driven by a motor is used, but is not limited thereto. The reformed water supplied from the reformed water supply unit 209 is vaporized by the evaporator 203 and sent to the reformer 202 through the reformed water channel 213 and the combustible gas channel 211.

  The combustible gas flow path 211 is a flow path from the power generation raw material supply device 205 to the anode 220 of the fuel cell 201 through the reformer 202, and a power generation raw material or hydrogen-containing gas that is a combustible gas flows therethrough. As shown in FIG. 18, the combustible gas channel 211 corresponds to a section from the power generation raw material supplier 205 to the downstream end of the anode 220 in the fuel cell 201. That is, the combustible gas channel 211 includes a channel for guiding the power generation material from the power generation material supply unit 205 to the reformer 202, and the hydrogen-containing gas generated by reforming the power generation material by the reformer 202. It is a flow path obtained by adding a flow path for guiding to the fuel cell 201.

  The oxidant gas flow path 212 is a flow path from the oxidant gas supply unit 206 to the cathode 221 of the fuel cell 201, and the oxidant gas flows therethrough. As shown in FIG. 18, the oxidant gas flow path 212 corresponds to a section from the oxidant gas supply unit 206 to the downstream end of the cathode 221 of the fuel cell 201.

  The reformed water flow path 213 is a flow path from the reformed water supply unit 209 to a merging section (not shown) on the upstream side of the reformer 202 in the flammable gas flow path 211. The channel 211 is connected. In the reforming water channel 213, water (steam) used in the reforming reaction performed in the reformer 202 flows.

  The fuel cell 201 uses the hydrogen-containing gas (reformed gas) supplied from the reformer 202 through the combustible gas channel 211 and the oxidant gas supplied through the oxidant gas channel 212 to generate power. For example, a solid oxide fuel cell that generates electricity by reaction can be exemplified. The fuel cell 201 includes an anode 220 to which a hydrogen-containing gas is supplied and a cathode 221 to which an oxidant gas is supplied, and a fuel cell single cell that generates power by performing a power generation reaction between the anode 220 and the cathode 221. Are connected in series to form a cell stack. The fuel cell 201 has the same configuration as the fuel cell 1 included in the fuel cell system 100 according to the first embodiment, and thus detailed description thereof is omitted.

  As shown in FIG. 18, a combustion unit 210 is provided at the rear stage of the fuel cell 201, and in this combustion unit 210, hydrogen-containing gas and oxidant gas that are unused for power generation of the fuel cell 201 are flame-combusted. It is configured. The flame combustion generates heat necessary for the fuel cell 201, the reformer 202, and the like, and the generated combustion exhaust gas is discharged out of the system through a combustion exhaust gas channel (not shown). ing. Before the combustion exhaust gas is discharged out of the system, for example, a heat exchanger is provided in the middle of the combustion exhaust gas channel 214, and the oxidant gas is raised by heat exchange with the oxidant gas sent to the cathode 221. It is good also as a structure heated. With this configuration, the fuel cell system 200 can be operated with a higher energy utilization rate.

  As will be described in detail later, in the fuel cell system 200, the combustible gas passage 211 is purged using the hydrogen-containing gas obtained by reforming the power generation material in the operation stop process, and the oxidant gas is used using the oxidant gas. Each channel 212 is purged. Therefore, when purging is performed in the operation stop process, the hydrogen-containing gas is introduced from the anode 220 side of the fuel cell 201 and the oxidant gas is introduced from the cathode 221 side of the fuel cell 201 to the combustion unit 210. And in this combustion part 210, it is good also as a structure which ignites hydrogen containing gas and carries out a flame combustion with oxidizing gas.

  The reformer 202 generates a hydrogen-containing gas by a reforming reaction using a power generation raw material and reforming water (steam). Examples of the reforming reaction performed in the reformer 202 include a steam reforming reaction.

  In addition, the fuel cell system 200 includes an evaporator 203 that generates steam and a heater 204 that heats the evaporator 203 to a predetermined temperature when the steam reforming reaction is performed as a reforming reaction.

  The heater 204 heats the evaporator 203 until it reaches a predetermined temperature range at the start of startup of the fuel cell system 200. Further, the heater 204 heats the evaporator 203 when the temperature of the evaporator 203 becomes a predetermined temperature or lower in the operation stop process. As the heater 204, for example, an electric heater can be used.

  Note that the evaporator 203 is heated and maintained in a predetermined temperature range by the heater 204 not only at the start of startup and when the operation is stopped, but also during the steady operation of the fuel cell system 200. Also good. Alternatively, during the steady operation of the fuel cell system 200, the heater 203 may not be activated, and the evaporator 203 may be maintained in a predetermined temperature range by the heat of the combustion exhaust gas generated in the combustion unit 210.

  Examples of the power generation material supplied to the fuel cell system 200 are the same as the power generation material supplied to the fuel cell system 100.

  The controller 208 controls various operations of each part of the fuel cell system 200. For example, after the power generation of the fuel cell 201 is stopped in the operation stop process of the fuel cell system 200, the controller 208 controls the power generation raw material supply unit 205 to supply the power generation raw material to the combustible gas passage 211, and the power generation raw material. As the water is replenished, the reforming water supplier 209 and the evaporator 203 are controlled so that water vapor flows into the combustible gas flow path 211 and the reformer 202 generates a hydrogen-containing gas. On the other hand, the controller 208 controls the oxidant gas supply unit 206 to supply the oxidant gas to the oxidant gas channel 212. Note that the combustible gas flow path 211 and the oxidant gas flow path 212 are joined at the combustion section 210 provided at the rear stage of the fuel cell 201. For this reason, the controller 208 supplies the oxidant gas so as to prevent the hydrogen-containing gas flowing through the combustible gas channel 211 from flowing into the oxidant gas channel 212 and reducing and degrading the cathode 221. The period during which the power generation raw material is supplied and the period during which the oxidant gas is supplied need not necessarily coincide.

  Furthermore, the controller 208 may be configured such that the elapsed time from when the power generation of the fuel cell 201 is stopped in the operation stop process or the elapsed time after receiving a signal indicating an operation instruction for operation stop, or the temperature of the fuel cell 201, The activation of the heater 204 is controlled according to the temperature of the reformer 202 or the temperature of the evaporator 203. And the controller 208 raises the temperature of the evaporator 203 by starting the heater 204, and makes it become the temperature range which can vaporize water.

  That is, the controller 208 is provided with a timing unit (not shown), receives time information measured by the timing unit, and gives an elapsed time from when the fuel cell 201 stops power generation or an operation instruction to stop operation. It is possible to grasp the elapsed time after receiving the signal shown. The fuel cell 201 has a fuel cell temperature detector T10 as a temperature detector, the reformer 202 has a reformer temperature detector T20 as a temperature detector, and the evaporator 203 has an evaporator temperature as a temperature detector. Detectors T30 are provided, and the controller 208 can recognize the temperatures of the fuel cell 201, the reformer 202, and the evaporator 203 by receiving temperature information from each of them. The fuel cell temperature detector T10, the reformer temperature detector T20, and the evaporator temperature detector T30 can be configured with a thermocouple, a thermistor, or the like. In the second embodiment of the present invention, the controller 208 includes a fuel cell temperature detector T10, a reformer temperature detector T20, and an evaporator temperature detector T30 as temperature detectors. The controller 208 may be configured to receive temperature information.

  The controller 208 only needs to have a control function, and can have the same configuration as the controller 8 according to the first embodiment.

  The storage device 207 associates a control program (not shown) executed by the arithmetic processing unit with temperature changes of the temperatures of the fuel cell 201, the reformer 202, and the evaporator 203 that have been examined in advance through experiments or the like. The table 230 is stored. This table 230 also records predetermined temperatures, which will be described later, set in the temperature fluctuation ranges of the fuel cell 201, the reformer 202, and the evaporator 203.

(Fuel cell system shutdown process)
Next, a specific example of the operation stop process of the fuel cell system 200 according to Embodiment 2 of the present invention will be described with reference to FIGS. 19 and 20 are flowcharts showing an example of the operation stop process of the fuel cell system 200 according to Embodiment 2 of the present invention. The operation shown in the flowchart can be realized by the controller 208 reading and executing a control program (not shown) stored in the storage device 207, for example.

First, in the operation stop process, an operation to stop operation is started (step S210). In the fuel cell system 200, the controller 208 controls the power generation raw material supply unit 205, the reforming water supply unit 209, and the fuel cell 201 to stop the supply of the power generation raw material and the reforming water by starting the operation of stopping the operation. Then, the power generation of the fuel cell 201 is stopped. That is, the controller 208 receives an operation stop operation instruction from an operator or the like via an input device (not shown) or the like, or determines that the operation is stopped based on a predetermined condition. The supply to the combustible gas flow path 211 is stopped, and the reforming water supplier 209 is controlled to stop the supply of the reforming water to the evaporator 203. However, the controller 208 continues supplying the oxidant gas to the oxidant gas flow path 212 for a while (for example, 5 minutes) (step S211). Then, the controller 208 determines time for supplying the oxidizing gas, the operation stop operation start to a predetermined time t ₁ or from elapsed whether determined (step S212), and a predetermined time has elapsed t ₁ or more Then ("YES" in step S212), the oxidant gas supply unit 206 is controlled to stop the supply of oxidant gas (step S213).

Thus, in the fuel cell system 200, thereby continuing the supply of the oxidizing gas from the shutdown operation is initiated at step S210 until a predetermined time t ₁ has elapsed. This is due to the following reason. In other words, immediately after the start of the operation stop operation in step S210, the already supplied reforming water (steam) remains in the reforming water flow path. For this reason, immediately after the start of the operation stop operation step, the hydrogen-containing gas is generated in the reformer 202 and supplied to the fuel cell 201. That is, with the supply of the power generation raw material and the supply of reforming water (steam) immediately before the shutdown, hydrogen-containing gas is generated in the reformer 202 for a while after the shutdown instruction. Here, in the operation stop process, the combustible gas flow path 211 has a pressure higher than that of the oxidant gas flow path 212, so that the generated hydrogen-containing gas is a combustion section 210 provided at the rear stage of the fuel cell 201. May flow into the cathode 221 side of the fuel cell 201. In order to prevent the hydrogen-containing gas from flowing into the cathode 221, the fuel cell system 200 supplies the oxidant gas to the oxidant gas flow channel 212 until a predetermined time t ₁ elapses after the operation stop operation is started. It is configured to make it. The predetermined time t ₁ is a time during which the hydrogen-containing gas does not flow into the cathode 221 side of the fuel cell 201 after the operation stop operation is started, that is, the hydrogen-containing gas in the reformer 202 after the operation stop operation. Can be defined as the time until no longer occurs.

Next, the controller 208 determines the magnitude relationship between the fuel cell temperature detected by the fuel cell temperature detector T10 and the predetermined temperature T _s1 . Alternatively, the controller 208 determines the magnitude relationship between the reformer temperature detected by the reformer temperature detector T20 and the predetermined temperature _Tr1 . Alternatively, the controller 208 determines the magnitude relationship between the evaporator temperature detected by the evaporator temperature detector T30 and the predetermined temperature T _e1 (step S214). That is, the controller 208 determines the magnitude relationship between at least one of the fuel cell temperature, the reformer temperature, and the evaporator temperature and the predetermined temperature.

  Here, the fuel cell 201 and the reformer 202 are configured to be heated by heat generated by the combustion of the combustible gas in the combustion unit 210 provided at the subsequent stage of the fuel cell 201. For this reason, the temperature of both the fuel cell 201 and the reformer 202 changes in conjunction. Further, the evaporator 203 is heated by the heat of the combustion exhaust gas generated in the combustion unit 210 during the steady operation, and after the start of the operation for stopping the operation, the temperature is lowered similarly to the fuel cell 201 and the reformer 202 described above. It is supposed to be. That is, the temperature change of each of the fuel cell 201, the reformer 202, and the evaporator 203 is interlocked after the start of the shutdown operation.

  Therefore, in the fuel cell system 200 according to Embodiment 2 of the present invention, the storage device 207 stores a table 230 that associates the temperature changes of the fuel cell temperature, the reformer temperature, and the evaporator temperature. Then, the controller 208 refers to the table 230, and can grasp one of the fuel cell temperature, the reformer temperature, and the evaporator temperature, thereby grasping the remaining temperature.

The fuel cell temperature is the temperature of an arbitrary single cell constituting the fuel cell 201, but is not limited to this. For example, the temperature of the combustible gas or oxidant gas flowing through the fuel cell 201 may be used. The predetermined temperature T _s1 may be the temperature of the fuel cell 201 immediately after the start of the operation stop process of the fuel cell system 200, or the temperature of the fuel cell 201 after a predetermined time has elapsed from the start of the operation stop process. For example, the temperature may be 480 ° C.

The reformer temperature is the temperature of the reforming catalyst charged in the reformer 202, and the predetermined temperature T _r1 can be set to 480 ° C., for example. That is, during the operation stop process, the temperature of the fuel cell 201 and the reformer 202 is substantially the same temperature. Further, the evaporator temperature is a temperature at a predetermined position in the evaporator 203, and the predetermined temperature T _e1 can be set to 180 ° C., for example.

Here, after the start of the shutdown operation, as described above, the fuel cell temperature, the reformer temperature, and the evaporator temperature change in conjunction with each other. Therefore, in step S214, the controller 208 determines whether the fuel cell temperature is equal to or lower than the predetermined temperature T _s1 , whether the reformer temperature is equal to or lower than the predetermined temperature T _r1 , and the evaporator temperature is equal to or lower than the predetermined temperature T _e1 . If at least one of the determinations regarding whether or not there satisfies the determination condition (“YES” in step S214), the controller 208 controls the oxidant gas supply unit 206 to control the oxidant gas flow path of the oxidant gas. Supply to 212 is started (step S215). Next, the controller 208 controls the reforming water supply unit 209 to start the supply of the reforming water to the reforming water channel 213 (step S216) and also controls the power generation raw material supply unit 205 to control the combustible gas flow. Supply of the power generation raw material to the path 211 is started (step S217).

  As described above, in the fuel cell system 200 according to the present embodiment, the oxidant gas flow path 212 is purged by supplying the oxidant gas, and the power generation raw material and the reforming water (steam) are supplied. The combustible gas passage 211 is purged with the hydrogen-containing gas generated in the vessel 202.

  Thereafter, as the temperature of each part of the fuel cell system 200 (for example, the fuel cell 201, the reformer 202, the evaporator 203, etc.) decreases with time, the reformer water may be vaporized in the evaporator 203. It becomes difficult. When it becomes difficult to evaporate the reforming water in the evaporator 203, the hydrogen concentration in the hydrogen-containing gas generated in the reformer 202 decreases, and the combustion of the hydrogen-containing gas in the combustion unit 210 becomes difficult. Go.

Therefore, the controller 208 detects the fuel cell temperature detected by the fuel cell temperature detector T10, the reformer temperature detected by the reformer temperature detector T20, and the evaporator detected by the evaporator temperature detector T30. Accept at least one of the temperatures and monitor the temperature change. Then, the controller 208 determines the magnitude relationship between the fuel cell temperature and the predetermined temperature T _s2 . Alternatively, the controller 208 determines the magnitude relationship between the reformer temperature and the predetermined temperature _Tr2 . Alternatively the controller 208 determines the magnitude relation between the evaporator temperature and the predetermined temperature _{T e2} (step S218). Here, the controller 208 determines whether the fuel cell temperature is equal to or lower than the predetermined temperature T _s2 , whether the reformer temperature is equal to or lower than the predetermined temperature T _r2 , or whether the evaporator temperature is equal to or lower than the predetermined temperature T _e2. . If at least one of these satisfies the determination condition (“YES” in step S218), the heater 204 is operated to heat the evaporator 203 (step S219). Conversely, when the determination condition of step S218 is not satisfied, the supply of the oxidant gas, the reforming water, and the power generation raw material is continued. In addition, the case where the determination condition of step S218 is satisfied is a case where the temperature is equal to or lower than the lower limit value of the operating temperature of the evaporator 203 that can vaporize the reforming water.

  Thus, in the fuel cell system 200 according to the present embodiment, when it is determined that the operating temperature of the evaporator 203 is equal to or lower than the lower limit value, the vaporization of the reforming water is continued by heating the evaporator 203, Water vapor can be supplied to the combustible gas channel 211. Therefore, it becomes difficult to evaporate the reforming water due to the temperature of the evaporator 203 being lowered, and the hydrogen concentration in the hydrogen-containing gas produced by the reformer 202 can be prevented from being lowered.

The predetermined temperature T _s2 , the predetermined temperature T _r2 , and the predetermined temperature T _e2 are the fuel cell temperature, the reformer temperature, and the evaporator when the evaporator 203 becomes a temperature at which the reforming water cannot be sufficiently vaporized. Temperature. For example, the predetermined temperature T _s2 of the fuel cell temperature can be about 300 ° C., the predetermined temperature T _r2 of the reformer temperature is about 300 ° C., and the predetermined temperature T _e2 of the evaporator 203 is about 100 ° C. can do.

Further, the controller 208 receives at least one of the fuel cell temperature detected by the fuel cell temperature detector T10 and the reformer temperature detected by the reformer temperature detector T20, and monitors the temperature change. Then, the controller 208 determines the magnitude relationship between the detected fuel cell temperature and the predetermined temperature T _s3 . Alternatively, the controller 208 determines the magnitude relationship between the detected reformer temperature and the predetermined temperature _Tr3 (step S220).

Here, the controller 208 determines whether or not the detected fuel cell temperature is equal to or lower than the predetermined temperature T _s3 , and whether or not the reformer temperature is equal to or lower than the predetermined temperature T _r3 , and at least one of them is determined. If the condition satisfies the determination condition (“YES” in step S220), it is determined that the temperature has reached a point at which the anode 220 of the fuel cell 201 is not likely to be oxidized. Therefore, if “YES” in step S220, the controller 208 controls the power generation material supply unit 205 to stop the supply of power generation material (step S221) and also controls the reforming water supply unit 209 to perform reforming. Water supply is stopped (step S222). Furthermore, the controller 208 stops the operation of the heater 204 (step S223). In addition, the execution order of step S221-step S223 is not limited to this order, respectively, You may implement simultaneously and each order may be changed.

The predetermined temperature T _s3 and the predetermined temperature T _r3 are the fuel cell temperature and the reformer temperature at which the anode 220 of the fuel cell 201 is not likely to be oxidized. For example, the predetermined temperature T _s3 of the fuel cell temperature can be set to 150 ° C. to suppress oxidation due to local cell generation, and the predetermined temperature of the reformer temperature can also be set to 150 ° C.

In this manner, when the supply of the power generation raw material and the reforming water (steam) is stopped, the generation of the hydrogen-containing gas in the reformer 202 is stopped. However, the generation of the hydrogen-containing gas is not stopped immediately after the controller 208 stops supplying the power generation raw material and the supply of reforming water is stopped. Immediately before the stop instruction of the controller 208, there are power generation raw materials and reformed water flowing toward the reformer 202, and a hydrogen-containing gas is generated with a delay after the stop instruction. Therefore, in order to prevent the hydrogen-containing gas generated after the stop instruction from flowing into the cathode 221 side of the fuel cell 201 and reducing the cathode 221, until a predetermined time t ₂ elapses after the operation of the heater 204 is stopped. Continue to supply oxidant gas. That is, the controller 208, the supply of the oxidizing gas after the stop of the operation of the heater 204 a predetermined time t ₂ or more, it is determined whether or not to continue, the predetermined time t ₂ or more, if it is determined that the continued oxidant The gas supplier 206 is controlled to stop the supply of the oxidant gas (step S225).

  As described above, the fuel cell system 200 according to the present embodiment can perform the operation stop process. As described above, the hydrogen-containing gas generated in the reformer 202 until the temperature of the fuel cell 201, the reformer 202, etc. is lowered to a temperature at which the anode 220 of the fuel cell 201 is no longer oxidized. Purge with gas. For this reason, air flows from the outside in response to a pressure drop due to gas contraction in the combustible gas flow path as the temperature of the fuel cell 201 decreases and a pressure drop in the combustible gas flow path caused by condensation of water vapor. Can be prevented. Therefore, in addition to oxidation by air downstream of the anode 220 at low temperatures, oxidation due to local cell generation upstream of the anode 220 due to intrusion of air from the downstream side of the anode 220 can be suppressed.

  In addition, since the power generation raw material itself does not purge the combustible gas channel 211 using a hydrogen-containing gas, it prevents carbon from being deposited on the anode 220 and the reformer 202 of the fuel cell 201. Can do.

  In carrying out this shutdown process, the combustible gas discharged from the fuel cell 201 is burned by operating an igniter (not shown) in the combustion unit 210 during a period in which the power generation raw material and reforming water are supplied. In addition, it may be configured to exhaust to the outside of the system. When comprised in this way, it can prevent that combustible gas is discharged | emitted out of the system as it is.

  In addition, the oxidant gas, the reforming water, and the power generation raw material that have been supplied in steps S215, 216, and 217 may be continuously supplied until the supply is stopped in steps S221, 222, and 225, respectively. , May be supplied intermittently. When the oxidant gas, the reforming water, and the power generation raw material are intermittently supplied, the controller 208 receives time information from a timing unit (not shown) and supplies the oxidant gas, the reforming water, and the power generation raw material for a predetermined period. In addition, the reforming water supply unit 209, the power generation material supply unit 205, and the oxidant gas supply unit 206 are controlled so that the operation of stopping the supply for a predetermined period is repeated a predetermined number of times. Alternatively, the oxidant gas may be supplied intermittently as described above while continuously supplying the oxidant gas from the start in step S215 until the supply is stopped in step S225. Good. When it is set as the structure which supplies an electric power generation raw material and reforming water intermittently, the electric power generation raw material consumed when implementing an operation stop process in the fuel cell system 200 can be reduced.

  Further, the heater 204 whose operation is started in step S219 may be configured to continue to operate until the operation ends in step S223. Alternatively, the heater 204 may be configured to be ON / OFF controlled by the controller 208 so that the evaporator temperature is within a predetermined temperature range, or may be configured to be PWM (Pulse Width Modulation) controlled. May be.

  Further, in the fuel cell system 200 according to the present embodiment, the temperature detector is configured to include the fuel cell temperature detector T10, the reformer temperature detector T20, and the evaporator temperature detector T30. It is not always necessary to provide these three, and it is sufficient to provide at least one of them.

  Further, the fuel cell system 200 according to the present embodiment may further include a desulfurizer (not shown in FIG. 18) for removing sulfur compounds contained in the power generation raw material in the combustible gas passage 211. Good. When configured in this manner, the desulfurizer is provided between the power generation raw material supply unit 205 and the reformer 202 in the combustible gas flow path 211. The desulfurizer may have the same configuration as the desulfurizer 9 provided in the fuel cell system 100 according to the second modification of the first embodiment.

  The sulfur compound contained in the power generation raw material may be artificially added to the raw material as an odorant component, or may be a natural sulfur compound derived from the raw material itself. Specifically, tertiary-butylmercaptan (TBM), dimethylsulfide (DMS), tetrahydrothiophene (THT), carbonyl sulfide (COS), hydrogen sulfide, etc. Illustrated.

(Modification 1 of Embodiment 2)
(Configuration of Fuel Cell System According to Modification 1 of Embodiment 2)
Next, the configuration of the fuel cell system 200 according to Modification 1 of Embodiment 2 of the present invention will be described with reference to FIG. FIG. 21 is a block diagram showing an example of a schematic configuration of a fuel cell system 200 according to Modification 1 of Embodiment 2 of the present invention.

  As shown in FIG. 21, the fuel cell system 200 according to Modification 1 of Embodiment 2 is different from the configuration of the fuel cell system 200 shown in FIG. 18 in that a purifier 231 is further provided in the combustion exhaust gas channel 214. . Further, the purifier 231 is different in that a purifier temperature detector T40 is provided. Since it becomes the same structure about other points, the same code | symbol is attached | subjected to the same member and the description is abbreviate | omitted.

  As shown in FIG. 21, on the downstream side of the combustion section 210, a combustion exhaust gas passage 214 is provided through which combustible gas is combusted in the combustion section 210 and the generated combustion exhaust gas flows. When combustion is not performed in the combustion unit 210 after the fuel cell 201 is stopped, the combustion exhaust gas flow path 214 contains a combustible gas (hydrogen-containing gas) discharged from the fuel cell 201 and an oxidant gas. Exhaust gas circulates.

  The purifier 231 is provided in the combustion exhaust gas passage 214 and purifies the exhaust gas discharged from the fuel cell 201 flowing through the combustion exhaust gas passage 214. This exhaust gas is a highly flammable gas. The configuration of the purifier 231 is the same as that of the purifier 16 included in the fuel cell system 100 according to the third modification of the first embodiment, and thus detailed description thereof is omitted.

  The purifier 231 may be configured to be heated to a predetermined temperature range by the combustion exhaust gas flowing through the combustion exhaust gas passage 214 during the steady operation of the fuel cell system 200. In other words, during steady operation, the combustion exhaust gas that has passed through the purifier 231 is discharged out of the fuel cell system 200 in a state where the highly combustible gas is purified while heating the purifier 231 as described above. The

  The purifier 231 is provided with the purifier temperature detector T40 as described above, and information on the temperature (purifier temperature) detected by the purifier temperature detector T40 is output to the controller 208. The purifier temperature detector T40 can be composed of, for example, a thermocouple or a thermistor.

(Operation stop process of fuel cell system according to Modification 1 of Embodiment 2)
Next, the operation stop process of the fuel cell system 200 according to Modification 1 of Embodiment 2 having the above-described configuration will be described with reference to FIGS. 22 and 23 are flowcharts showing an example of the operation stop process of the fuel cell system 200 according to Modification 1 of Embodiment 2 of the present invention. The operation shown in the flowchart can be realized by the controller 208 reading and executing a control program (not shown) stored in the storage device 207, for example.

  In the flowcharts shown in FIGS. 22 and 23, the processing from step S230 to step S233, the processing from step S235 to step S237, the processing from step S239, and step S241 to step S245 are described in FIGS. Since the processing from step S210 to step S213 shown, the processing from step S215 to step S217, the processing from step S219, and from step S221 to step S225 are the same, description thereof will be omitted.

After the supply of the oxidant gas is stopped in step S233, in the subsequent step S234, the controller 208 determines the magnitude relationship between the fuel cell temperature detected by the fuel cell temperature detector T10 and the predetermined temperature T _s1 . Alternatively, the controller 208 determines the magnitude relationship between the reformer temperature detected by the reformer temperature detector T20 and the predetermined temperature _Tr1 . Alternatively, the controller 208 determines the magnitude relationship between the evaporator temperature detected by the evaporator temperature detector T30 and the predetermined temperature _Te1 . Alternatively, the controller 208 determines the magnitude relationship between the purifier temperature detected by the purifier temperature detector T40 and the predetermined temperature _Tp1 . That is, the controller 208 determines a magnitude relationship between at least one of the fuel cell temperature, the reformer temperature, the evaporator temperature, and the purifier temperature and the predetermined temperature.

  Here, the fuel cell 201 and the reformer 202 are configured to be heated by heat generated by the combustion of the combustible gas in the combustion unit 210 provided at the subsequent stage of the fuel cell 201. For this reason, the temperature of both the fuel cell 201 and the reformer 202 changes in conjunction. Further, the evaporator 203 and the purifier 231 are heated by the heat of the combustion exhaust gas generated in the combustion section 210 during the steady operation, and after the start of the operation stop operation, the fuel cell 201 and the reformer 202 described above are heated. Similarly, the temperature decreases. That is, after the start of the shutdown operation, the temperature changes of the fuel cell 201, the reformer 202, the evaporator 203, and the purifier 231 are linked.

  Note that the table 230 stored in the storage device 207 of the fuel cell system 200 according to the first modification of the second embodiment of the present invention includes temperature fluctuations of the fuel cell 201, the reformer 202, and the evaporator 203. In addition to the predetermined temperature set in the range, the predetermined temperature set in the temperature fluctuation range of the purifier 231 is recorded.

The purifier temperature is the temperature of the purifying catalyst charged in the purifier 231, but is not limited to this. The predetermined temperature T _p1 of the purifier 231 may be the temperature of the purifier 231 immediately after the start of the operation stop process of the fuel cell system 200, or the purifier after a predetermined time has elapsed since the start of the operation stop process. The temperature may be 231. In step S234 of the operation stop process, when the predetermined temperature T _s1 of the fuel cell 201 is about 480 ° C., the predetermined temperature T _p1 of the purifier 231 is, for example, about 270 ° C.

Here, after the start of the operation for stopping the operation, as described above, the fuel cell temperature, the reformer temperature, the evaporator temperature, and the purifier temperature change in conjunction with each other. For this reason, in step S234, the controller 208 determines whether the fuel cell temperature is equal to or lower than the predetermined temperature T _s1 , whether the reformer temperature is equal to or lower than the predetermined temperature T _r1 , or the evaporator temperature is equal to or lower than the predetermined temperature T _e1. If at least one of the determinations as to whether the purifier temperature is equal to or lower than the predetermined temperature T _p1 satisfies the determination condition (“YES” in step S234), the controller 208 changes the oxidant gas supply unit 206 to The supply of the oxidant gas to the oxidant gas channel 212 is started under control (step S235). Further, in steps S236 and S237, the supply of the reforming water and the power generation raw material is started, and the oxidant gas passage 212 and the combustible gas passage 211 are purged.

  Thereafter, as the temperature of each part (for example, the fuel cell 201, the reformer 202, the evaporator 203, and the purifier 231) of the fuel cell system 200 decreases with the passage of time, first the reformer water is supplied to the evaporator 203. It becomes difficult to vaporize.

Therefore, the controller 208 detects the fuel cell temperature detected by the fuel cell temperature detector T10, the reformer temperature detected by the reformer temperature detector T20, and the evaporator temperature detected by the evaporator temperature detector T30. At least one of the purifier temperatures detected by the purifier temperature detector T40 is received and the temperature change is monitored. Then, the controller 208 determines the magnitude relationship between the fuel cell temperature and the predetermined temperature T _s2 . Alternatively, the controller 208 determines the magnitude relationship between the reformer temperature and the predetermined temperature _Tr2 . Alternatively, the controller 208 determines the magnitude relationship between the evaporator temperature and the predetermined temperature _Te2 . Alternatively, the controller 208 determines the magnitude relationship between the purifier temperature and the predetermined temperature T _p2 (step S238).

Here, the controller 208 determines whether the fuel cell temperature is equal to or lower than the predetermined temperature T _s2 , whether the reformer temperature is equal to or lower than the predetermined temperature T _r2 , whether the evaporator temperature is equal to or lower than the predetermined temperature T _e2 , or purification. It is determined whether the vessel temperature is equal to or lower than a predetermined temperature _Tp2 . If at least one of these satisfies the determination condition (“YES” in step S238), the heater 204 is operated to heat the evaporator 203 (step S239). On the contrary, when the condition of step S238 is not satisfied, the supply of the oxidizing gas, the reforming water, and the power generation raw material is continued.

  As described above, in the fuel cell system 200 according to Embodiment 2 of the present invention, the vaporization of the reforming water can be continued by heating the evaporator 203 and the water vapor can be supplied to the combustible gas channel 211. Therefore, it becomes difficult to evaporate the reforming water due to the temperature of the evaporator 203 being lowered, and the hydrogen concentration in the hydrogen-containing gas produced by the reformer 202 can be prevented from being lowered.

The predetermined temperature T _p2 is a purifier temperature corresponding to the evaporator temperature when the evaporator 203 reaches a temperature at which the reforming water cannot be sufficiently vaporized. In step S238 of the operation stop process, for example, the predetermined temperature T _p2 of the purifier 231 can be about 200 ° C. At this time, the predetermined temperature T _s2 of the fuel cell 201 corresponding to the temperature of the purifier 231 is about 300 ° C.

Further, the controller 208 includes the fuel cell temperature detected by the fuel cell temperature detector T10, the reformer temperature detected by the reformer temperature detector T20, and the purifier temperature detected by the purifier temperature detector T40. Accept at least one of them and monitor the temperature change. Then, the controller 208 determines the magnitude relationship between the detected fuel cell temperature and the predetermined temperature T _s3 . Alternatively, the controller 208 determines the magnitude relationship between the detected reformer temperature and the predetermined temperature _Tr3 . Alternatively, the controller 208 determines the magnitude relationship between the detected purifier temperature and the predetermined temperature T _p3 (step S240).

Here, the controller 208 determines whether the fuel cell temperature is equal to or lower than the predetermined temperature T _s3 , whether the reformer temperature is equal to or lower than the predetermined temperature T _r3 , and whether the purifier temperature is equal to or lower than the predetermined temperature T _p3 . If at least one of these satisfies the determination condition (“YES” in step S240), it is determined that the temperature has reached a temperature at which the anode 220 of the fuel cell 201 is not likely to be oxidized. Therefore, if “YES” in step S240, the controller 208 controls the power generation material supply unit 205 to stop the supply of power generation material (step S241) and also controls the reforming water supply unit 209 to perform reforming. Water supply is stopped (step S242). Furthermore, the controller 208 stops the operation of the heater 204 (step S243). Note that the steps of Step S241 to Step S243 are not limited to this order, and may be performed at the same time, or the respective orders may be changed.

The predetermined temperature T _p3 is a purifier temperature corresponding to the fuel cell temperature or the reformer temperature at which the anode 220 of the fuel cell 201 is no longer likely to be oxidized. In step S240 of the operation stop process, for example, the predetermined temperature T _p3 of the purifier 231 can be set to about 120 ° C. At this time, the predetermined temperature T _s3 of the fuel cell 201 corresponding to the temperature of the purifier 231 is about 150 ° C.

  As described above, in the fuel cell system 200 according to the first modification of the second embodiment, the supply or stop of the oxidant gas, the reforming water, the power generation raw material, and the operation of the heater 204 are performed even with respect to the temperature change of the purifier temperature. It can be a start or end trigger.

(Modification 2 of Embodiment 2)
In the above configuration, the temperature of the evaporator 203 can be maintained by operating the heater 204 so that the evaporator 203 has a temperature sufficient to vaporize the reforming water. However, even if the temperature of the evaporator 203 can be maintained in a predetermined temperature range as described above, the temperature at which the reforming reaction can proceed favorably in the reformer 202 due to the temperature drop in the operation stop process of the fuel cell 201. It may become lower than the range, and the hydrogen-containing gas may not be generated.

  Therefore, as a second modification, a fuel cell system 200 having a configuration capable of generating a hydrogen-containing gas even when the temperature falls below the temperature range in which the reformer 202 can function will be described.

(Configuration of Fuel Cell System According to Modification 2 of Embodiment 2)
A configuration of a fuel cell system 200 according to Modification 2 of Embodiment 2 of the present invention will be described with reference to FIG. FIG. 24 is a block diagram showing an example of a schematic configuration of a fuel cell system 200 according to Modification 2 of Embodiment 2 of the present invention.

  Compared with the configuration of the fuel cell system 200 shown in FIG. 18, the fuel cell system 200 according to Modification 2 of Embodiment 2 shown in FIG. 24 is arranged upstream of the reformer 202 in the combustible gas passage 211. This is different from the reformer 202 in that a pre-reformer 232 provided separately from the reformer 202 is further provided. Since it becomes the same structure about other points, the same code | symbol is attached | subjected to the same member and the description is abbreviate | omitted.

  Similar to the reformer 202, the pre-reformer 232 reforms the power generation raw material and supplies it to the fuel cell 201, and is configured to be filled with a reforming catalyst. As the reforming catalyst, the same catalyst as that of the reformer 202 may be used as long as the reforming reaction can proceed while maintaining the optimum temperature range. As shown in FIG. 24, the pre-reformer 232 is provided in the vicinity of or adjacent to the heater 204, and the temperature can be raised when the heater 204 is activated. Therefore, even when the reformer temperature detected by the reformer temperature detector T20 is, for example, 300 ° C. or less and the reforming reaction does not proceed well in the reformer 202, the heater 204 The preliminary reformer 232 is heated up to about 500 ° C. by which the reforming reaction proceeds satisfactorily. Thereby, the hydrogen-containing gas can be generated by the reforming reaction in the pre-reformer 232.

  That is, in the fuel cell system 200 according to the second modification of the second embodiment, when the controller 208 determines that the operating temperature of the evaporator 203 is equal to or lower than the lower limit value based on the detection result of the temperature detection unit, 204 can be controlled to heat the pre-reformer 232 together with the evaporator 203.

  Therefore, the fuel cell system 200 according to the second modification of the second embodiment includes the pre-reformer 232 that is heated by the heater 204 as described above. For this reason, even if the reforming reaction does not proceed sufficiently in the reformer 202 due to a temperature drop, the pre-reformer 232 heated by the heater 204 instead of the reformer 202 The reforming reaction can proceed to generate a hydrogen-containing gas.

(Modification 3 of Embodiment 2)
The fuel cell system 200 according to the modification 2 has a configuration in which a preliminary reformer 232 is provided on the upstream side of the reformer 202. However, the arrangement of the pre-reformer 232 is not limited to this, and the pre-reformer 232 may be configured as in a fuel cell system 200 according to Modification 3 below.

(Configuration of Fuel Cell System According to Modification 3 of Embodiment 2)
As shown in FIG. 25, the fuel cell system 200 according to Modification 3 has a configuration of the fuel cell system 200 according to Modification 2 in which the pre-reformer 232 includes the reformer 202 in the combustible gas channel 211. The configuration is arranged not on the upstream side but on the downstream side. FIG. 25 is a block diagram showing an example of a schematic configuration of a fuel cell system 200 according to Modification 3 of Embodiment 2 of the present invention.

  Incidentally, although not particularly shown in FIG. 25, a desulfurizer may be provided upstream of the reformer 202 in the combustible gas passage 211 to remove sulfur compounds contained in the power generation raw material. it can. By adopting the configuration including the deflower as described above, it is possible to prevent the reforming catalyst of the reformer 202 from being poisoned by the sulfur compound contained in the power generation raw material.

  However, even when the desulfurizer is provided as described above, sulfur compounds that could not be removed may flow into the reformer 202. In this case, there is a possibility that the reforming catalyst disposed particularly on the upstream side is poisoned by the sulfur compound.

  Therefore, in the fuel cell system 200 according to Modification 3 of Embodiment 2, the pre-reformer is disposed in the vicinity of or adjacent to the heater 204 and downstream of the reformer 202 in the combustible gas channel 211. 232 is provided. As a result, it is possible to prevent the preliminary reformer 232 from being poisoned by the sulfur compound contained in the power generation raw material and causing deterioration in the reforming performance. Therefore, the fuel cell system 200 according to the modification 3 can improve the durability of the preliminary reformer 232 as compared with the fuel cell system 200 according to the modification 2.

  In the fuel cell systems 200 of the second and third modifications of the second embodiment, the operation stop process is performed in the same manner as the control flow of the operation stop process shown in FIGS. Further, the fuel cell system 200 of the second and third modifications of the second embodiment may further include a purifier 231 and a purifier temperature detector T40, as in the fuel cell system 200 of the first modification of the second embodiment. Good. In the case of the configuration further including the purifier 231 and the purifier temperature detector T40 as described above, the control flow of the operation stop process performed in the fuel cell system 200 of the second and third modifications of the second embodiment is shown in FIGS. It becomes the same as the control flow of the operation stop process shown.

  As described above, the fuel cell system 200 according to the second and third modifications of the second embodiment further includes the pre-reformer 232 that is heated by the heater 204. For this reason, even if the reformer 202 falls below the temperature at which the reforming reaction can proceed satisfactorily due to the temperature drop after the fuel cell 201 is stopped, the preliminary reforming that has been heated by the heater 204 is performed. A reforming reaction can be carried out by the mass device 232 to generate a hydrogen-containing gas.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The solid oxide fuel cell system of the present invention can improve safety and durability, and can be widely applied in solid oxide fuel cell systems.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Reformer 3 Combustion part 4 Igniter 5 Power generation raw material supply 6 Oxidant gas supply 7 Reformation material supply 8 Controller 9 Desulfurizer 10 Reformation material flow path 11 Combustible gas flow path DESCRIPTION OF SYMBOLS 12 Oxidant gas flow path 13 Combustion exhaust gas flow path 14 Recycle flow path 15 Heating part 16 Purifier 20 Anode 21 Cathode 100 Fuel cell system 200 Fuel cell system 201 Fuel cell 202 Reformer 203 Evaporator 204 Heater 205 Supply of power generation raw material Unit 206 Oxidant gas supply unit 207 Storage device 208 Controller 209 Reformed water supply unit 210 Combustion unit 211 Combustible gas channel 212 Oxidant gas channel 213 Reformed water channel 214 Combustion exhaust gas channel 220 Anode 221 Cathode 230 Table 231 Purifier 232 Pre-reformer P Pressure sensor T1 Fuel cell temperature detector T2 Reformer temperature detector T3 Desulfurizer temperature detector T4 Purifier temperature detector T10 Fuel cell temperature detector T20 Reformer temperature detector T30 Evaporator temperature detector T40 Purifier temperature detector

Claims (15)

A solid oxide fuel cell;
A reformer for supplying a hydrogen-containing gas generated by reforming the power generation raw material to the anode of the solid oxide fuel cell;
A power generation material supplier for supplying the power generation material to the reformer;
A reforming material supplier for supplying at least one of reforming water and air used in the reforming reaction to the reformer;
An oxidant gas supplier for supplying an oxidant gas to the cathode of the solid oxide fuel cell;
Said to have a solid oxide fuel cell ignitor for igniting the ejected gas from the combustion section to the flue gas Ru is flame combustion,
A fuel cell system comprising a controller,
In the operation stop step of the fuel cell system, the controller controls the oxidant gas supply unit to supply the oxidant gas to the cathode of the solid oxide fuel cell, The reforming material supplier is controlled so that the power generation raw material and at least one of the water and air are intermittently supplied to the reformer, and the igniter included in the combustion unit is controlled. A fuel cell system that operates with ignition. A purifier that is disposed downstream of the combustion section and purifies the combustible gas contained in the combustion exhaust gas discharged from the combustion section;
A purifier the temperature detecting unit for detecting the temperature of the pre-Symbol purifier, further comprising a
2. The fuel cell system according to claim 1, wherein when the detection result by the purifier temperature detection unit is lower than a predetermined temperature, the controller controls the igniter to perform an ignition operation.   The fuel cell system according to claim 1 or 2, further comprising a desulfurizer for removing sulfur compounds contained in the power generation raw material.   4. The fuel cell system according to claim 3, further comprising a heating unit that circulates the exhaust gas burned in the combustion unit and heats the desulfurizer with heat of the burned exhaust gas.   The fuel cell system according to claim 3 or 4, wherein the desulfurizer is a hydrodesulfurizer that uses hydrogen to remove sulfur compounds from the power generation raw material.   The controller is configured to intermittently supply the power generation raw material and at least one of the water and air to the reformer at predetermined time intervals, the power generation raw material supply device and the reforming material. The fuel cell system according to any one of claims 1 to 5, wherein the fuel cell system is operated by operating a feeder. The temperatures of the reformer, the solid oxide fuel cell, and the desulfurizer change in conjunction with each other,
Before the reformer temperature detector for detecting the temperature of Kiaratame reformer, the fuel cell temperature detector for detecting the temperature of the solid oxide fuel cell, and the desulfurizer temperature detector for detecting the temperature of the desulfurizer At least one of them,
The controller intermittently supplies the power generation raw material and at least one of the water and air to the reformer, at least the reformer temperature detection unit, the fuel cell temperature detection unit, and The control is performed by controlling the power generation raw material supplier and the reforming material supplier in accordance with whether or not the temperature detected by any one of the desulfurizer temperature detectors is within a predetermined temperature range. 6. The fuel cell system according to any one of items 1 to 5.   The controller intermittently supplies the power generation raw material and at least one of the water and air to the reformer, at least the reformer temperature detection unit, the fuel cell temperature detection unit, and 8. The control according to claim 7, wherein the power generation raw material supply unit and the reforming material supply unit are controlled according to an increase value and a decrease value of the temperature detected by any one of the desulfurizer temperature detection units. Fuel cell system. A flammable gas flow path through which a flammable gas containing the power generation raw material flows, and a flow path from the power generation raw material supplier to the anode of the solid oxide fuel cell;
A pressure sensor provided in the combustible gas flow path and detecting a pressure in the combustible gas flow path,
In the detection result of the pressure sensor, when the pressure in the combustible gas flow path becomes a negative pressure, the controller includes the reformer of the power generation raw material and at least one of the water and air. 6. The fuel cell system according to claim 1, wherein intermittent supply to the fuel cell is performed by operating the power generation raw material supplier and the reforming material supplier at predetermined time intervals. A voltage detector for detecting the voltage of the solid oxide fuel cell;
Whenever the voltage detected by the voltage detector becomes a predetermined voltage or less, the controller supplies the power generation raw material and at least one of the water and air to the reformer. The fuel cell system according to any one of claims 1 to 5, wherein the power generation raw material supplier and the reforming material supplier are controlled. The reforming material supplier is a reforming water supplier that supplies reforming water to be used in a reforming reaction to the reformer,
An evaporator for vaporizing water supplied to the reformer from the reformed water supplier;
A heater for heating the evaporator;
An oxidant gas flow path, which is a flow path from the oxidant gas supply unit to the solid oxide fuel cell, through which the oxidant gas flows;
A flow path from the power generation raw material feeder to the anode of the solid oxide fuel cell, and a combustible gas flow path through which a combustible gas containing the power generation raw material flows ,
The temperatures of the evaporator, the reformer, and the solid oxide fuel cell are changed in conjunction with each other,
Evaporator temperature detecting unit for detecting the temperature of the pre-Symbol evaporator, the reformer temperature detector for detecting the temperature of the reformer, and fuel cell temperature detector for detecting the temperature of the solid oxide fuel cell Having at least one of them,
In the operation stop step of the fuel cell system, the controller controls the power generation raw material supply device and the reformed water supply device to distribute the power generation raw material and water to the combustible gas flow path. The oxidant gas supply device is controlled to cause the oxidant gas to flow through the oxidant gas flow path, and the evaporator temperature detection unit, the reformer temperature detection unit, and the fuel cell temperature detection based on at least one of the detection result of the part, when the operating temperature of the evaporator is determined as equal to or less than the lower limit, the claim 1 for controlling so as to heat the evaporator by the heater The fuel cell system according to any one of 5 . A purifier for purifying exhaust gas containing the combustible gas and the oxidant gas discharged from the fuel cell;
The temperature detector detects at least one of the temperatures of the purifier, which changes in conjunction with the temperatures of the evaporator, the reformer, and the fuel cell. the fuel cell system according to 1 1. Provided separately from the reformer, further comprising a pre-reformer for reforming the power generation raw material and supplying it to the fuel cell;
When the controller determines that the operating temperature of the evaporator has become lower than a lower limit value based on the detection result of the temperature detector, the controller causes the heater to heat the preliminary reformer together with the evaporator. the fuel cell system of claim 1 1 or 1 2 to control. In the operation stop process of the fuel cell system,
2. The fuel cell system according to claim 1, wherein when the power generation raw material is not supplied, the controller controls the igniter so as not to perform an ignition operation. In the operation stop step, when the temperature of the solid oxide fuel cell is 300 ° C. or lower, the controller intermittently supplies the power generation raw material and at least one of the water and air to the reformer. 2. The fuel cell system according to claim 1, wherein the fuel cell system is configured to be supplied and to perform an ignition operation by controlling the igniter of the combustion unit.

Images